UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 6-K

Report of Foreign Private Issuer

Pursuant to Rule 13a-16 or 15d-16 of

the Securities Exchange Act of 1934

Dated February 21, 2019

Commission File Number: 1-15018

Fibria Celulose S.A.

Fidêncio Ramos, 302 — 3rd and (part of) 4th floors

Edifício Vila Olímpia, Torre B, Bairro Vila Olímpia

04551-010, São Paulo, SP, Brazil

(Address of principal executive offices)

(Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F.)

Form 20-F: x Form 40-F: o

(Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1)):

Yes: o No: x

(Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7)):

Yes: o No: x

(Indicate by check mark whether the registrant by furnishing the information contained in this Form, the Registrant is also thereby furnishing the information to the Commission pursuant to Rule 12g3-2(b) under the Securities Exchange Act of 1934.)

Yes: o No: x

If “Yes” is marked, indicate below the file number assigned to the registrant in connection with Rule 12g3-2(b):

Resultados 4T18 4Q18 Results - Fibria Celulose S.A.

4Q18 Results Contents Key indicators............................................................................................................................... 3 Production and Sales ................................................................................................................... 3 Analysis of Results ....................................................................................................................... 4 Financial Income and Expenses .................................................................................................. 7 Net Income (Loss) ........................................................................................................................ 8 Debt ............................................................................................................................................. 9 Capital Expenditure .................................................................................................................... 11 Capital Markets .......................................................................................................................... 12 Appendix I – Gross Sales vs. Volume vs. Price ......................................................................... 13 Appendix II – Income Statement ................................................................................................ 14 Appendix III – Balance Sheet ..................................................................................................... 15 Appendix IV – Cash Flow ........................................................................................................... 16 Appendix V – Breakdown of EBITDA and Adjusted EBITDA (CVM Instruction 527/2012)......... 17 Appendix VI – Financial and Operating Data ............................................................................. 18 2

4Q18 Results The following stand-alone information pertains to Fibria Celulose S.A. Key indicators 3Q18 4Q17 Pulp Production 000 t 1,761 1,809 1,659 -3% 6% 6,758 5,642 20% Adjusted EBITDA(1) -40% -1% 93% R$ million 1,955 3,269 1,981 9,547 4,952 Net Financial Result(3) R$ million 432 (828) (781) - - (2,906) (783) 271% Dividends paid R$ million (2,786) (0) (0) - - (3,046) (395) 671% Gross Debt (R$) R$ million 20,667 21,351 19,299 -3% 7% 20,667 19,299 7% Net Debt (R$) R$ million 14,120 12,721 12,331 11% 15% 14,120 12,331 15% Net Debt/EBITDA LTM x 1.5 1.3 2.5 0.2 -1.0 1.5 2.5 -0.4 (1) Adjusted by non-recurring and non-cash items. | (2) Calculation excludes pulp sales f rom agreement w ith Klabin. (3) Includes interest expenses, revenues f rom f inancial investments, mark-to-market of hedging instruments, monetary and exchange variation and others. (4) Includes the hedge f air value. | (5) For covenants purposes. Production and Sales Production ('000 t) 4Q18 3Q18 4Q17 2018 2017 3Q18 4Q17 2017 Dom es tic Market Pulp 164 192 184 -14% -11% 704 662 6% In 4Q18, pulp production was 1,761 thousand tons, down 3% from 3Q18 and up 6% from 4Q17. The increase in annual comparison is mainly due to the evolution of the ramp-up at Horizonte 2. The calendar of maintenance and inspection shutdowns at Fibria units through 2020 follows: 12 months 15 months (1) V eracel is a joint operation betw een Fibria (50%) and StoraEnso (50%) and the total capacity is 1,120 thousand ton/year (2) In 2019 the dow ntime w ill take place at the end of the quarter, w hile in 2020, the Company expects the dow ntime f or the beginning of April. 3 Mills - capacity Aracruz A - 590 kt Aracruz B - 830 kt Aracruz C - 920 kt Jacareí - 1,100 kt Três Lagoas L1 - 1,300 kt Três Lagoas L2 - 1,950 kt Veracel - 560(1) kt 2020 1Q20 2Q20 3Q20 4Q20 2019 1Q19 2Q19 3Q19 4Q19 2018 1Q18 2Q18 3Q18 4Q18 No maintenance downtime 2017 1Q17 2Q17 3Q17 4Q17 No maintenance downtime No maintenance downtime No maintenance downtime Export Market Pulp 1,2751,7971,712-29%-26%6,0835,55010% Total sales1,4401,9881,897-28%-24%6,7876,2129% 4Q18 vs4Q18 vs2018 vs Pulp 1,7611,8091,659-3%6%6,7585,64220% Sales Volume ('000 t) Net Debt/EBITDA LTM (US$)(5)x1.41.22.40.2-1.01.42.4-0.4 Net Debt (US$)US$ million3,6443,1773,72815%-2%3,6443,728-2% Cash(4)R$ million6,5478,6306,968-24%-6%6,5476,968-6% Gross Debt (US$)US$ million5,3345,3325,834 0%-9% 5,3345,834 -9% Net IncomeR$ million 1,525 1,130 280 35%444% 3,0601,093 180% EBITDA margin pro-forma(2)%54%63%57%-9 p.p.-3 p.p.58%49%10 p.p. Pulp Sales000 t1,4401,9881,897-28%-24%6,7876,2129% Net RevenuesR$ million4,0135,8364,047 -31%-1% 18,26411,739 56% Key FiguresUnit4Q183Q184Q174Q18 vs4Q18 vs201820172018 vs 2017

4Q18 Results Sales volume came to 1,440 thousand tons, 28% and 24% lower compared to 3Q18 and 4Q17, respectively, due to the pressure from China on prices, which led Fibria to reduce its sales to Asia. In the quarter, sales volume from the agreement with Klabin totaled 135 thousand tons (3Q18: 229 thousand tons). In 4Q18, Europe accounted for 37% of net revenue, followed by North America (27%), Asia (25%) and Latin America (11%). Analysis of Results Net Revenues (R$ million) 4Q18 3Q18 4Q17 2018 2017 3Q18 4Q17 2017 Export Market Pulp 3,576 5,322 3,700 -33% -3% 16,530 10,621 56% Portocel 23 26 22 -12% 3% 97 92 5% Net revenue amounted to R$4,013 million in 4Q18, down 31% from 3Q18, largely due to lower sales volume (-28%) and the 4% depreciation of the average U.S. dollar against the Brazilian real. Compared to 4Q17, net revenue remained practically stable as result of the 17% depreciation in the average U.S. dollar exchange rate against the Brazilian real, the higher net pulp price in U.S. dollar (+12%), offset by the 24% decline in sales volume. Cost of goods sold (COGS) declined 26% and 15% from 3Q18 and 4Q17, respectively, mainly due to the lower sales volume. In terms of COGS per ton, freight per ton decreased 7% from 3Q18, mainly due to the sales mix resulting from lower sales to Asia and the impact of the exchange rate. Compared to 4Q17, freight per ton increased 11%, chiefly explained by the stronger U.S. dollar against the Brazilian real (17%). Pulp cash production cost in 4Q18 was R$ 638/t, up 9% from 3Q18, mainly due to the lower result from energy sales, higher wood costs due to higher specific consumption and higher labor costs (largely impacted by the resumption of a higher tax rate on payroll). Compared to 4Q17, cash cost increased 15%, primarily due to: (i) lower result from energy sales; (ii) higher wood cost, due to the higher average radius (4Q18: 261 km | 4Q18: 205 km), partially explained by the increased share of third-party wood from Losango; (iii) higher energy and chemical prices; and (iv) impact of the 17% appreciation of the U.S. dollar against the Brazilian real. Cash Cost (quarter) (R$/t) Cash Cost (year) (R$/t) Production Cash Cost 4Q18 638 638 647 637 618 619 Fixed costs 19% 556 546 Wood 46% Input 35% 4Q17 3Q18 4Q18 2017 2018 Variable costs Fixed costs with downtimes ex-downtimes with downtimes ex-downtimes 4 584 584 Total4,0135,8364,047-31%-1%18,26411,73956% Total Pulp 3,9905,8104,025-31%-1%18,16711,64756% 4Q18 vs4Q18 vs2018 vs Dom es tic Market Pulp 414488325-15%28%1,6371,02660%

4Q18 Results Pulp Cash Cost ex-downtime (R$/ton) 29 618 619 2017 Cash Cost ex-downtimes Wood Input Fixed Cost 2018 Cash Cost ex-downtimes Pulp cash cost in 2018 was 619/t excluding shutdowns (vs. R$ 618/t in 2017) and R$647/t including shutdowns (vs. R$637/ton in 2017). Pulp Cash Cost ex-downtime (R$/ton) 12 638 54 4Q17 Cash Cost ex-downtimes Wood Input Fixed Cost 4Q18 Cash Cost ex-downtimes Selling expenses came to R$175 million in 4Q18, down 25% from 3Q18, mainly due to the lower sales volume. The same reason explains the 6% decrease compared to 4Q17. Selling expenses as a ratio of net revenue were 4% (3Q18: 4% | 4Q17: 5%). General and administrative expenses totaled R$124 million, increasing 24% and 43%, respectively, from 3Q18 and 4Q17, primarily due to higher expenses with outsourced services. General and administrative expenses as a ratio of net revenue stood at 3%, up 1 p.p. from 3Q18 and 4Q17. Other operating expenses amounted to R$335 million in 4Q18, compared to other operating expenses of R$61 million in 3Q18 and R$118 million in 4Q17. The variation compared to 3Q18 is chiefly due to: (i) higher expenses with variable compensation, which, in turn, was impacted by the liability resulting from the transaction with Suzano (Commitment to Voting and Assumption of Obligations – Appendix C – item 7 (xi)); and (ii) the revaluation of biological assets. Compared to 4Q17, the variation is mainly due to the impact of variable compensation plans (explained above), increase in contingencies and asset write-offs, which were partially offset by lower expenses resulting from the revaluation of biological assets. 5 546 26 123 111 222 168 293 266 122 (20) (8) 114 182 211 314 294

4Q18 Results Adjusted EBITDA (R$ and US$ million) and EBITDA Margin (%)(1) Adjusted EBITDA/t(1) 63% 57% 54% 3,269 1,858 4Q18 3Q18 4Q17 4Q18 Adjusted EBITDA (R$ million) 3Q18 4Q17 Adjusted EBITDA (US$ million) Adjusted EBITDA R$/ton Adjusted EBITDA US$/ton (1) Excludes volume sold due to the agreement with Klabin Adjusted EBITDA in 4Q18 totaled R$1,955 million, with EBITDA margin of 54% (excluding revenue from the agreement with Klabin). The decline in relation to 3Q18 is mainly explained by lower sales volume (-28%), the increase in other operating expenses, as explained above, and the 4% depreciation in the average U.S. dollar against the Brazilian real during the period, partially offset mostly by lower cash COGS, which, in turn, is explained by the lower sales volume. Compared to 4Q17, adjusted EBITDA remained practically stable, mainly due to the decline in sales volume and the increase in other operating expenses, offset by the 12% increase in the average net price in U.S. dollar and the 15% appreciation of the average U.S. dollar against the Brazilian real. The following chart shows the main variations in the quarter: Adjusted EBITDA 4Q18 vs. 3Q18 (R$ million) 3,269 3,262 (24) (1,617) (206) 3Q18 Adjusted EBITDA Non-recurring effects / non-cash (1) 3Q18 EBITDA Volume COGS S&M G&A Other oper. Expenses 4Q18 EBITDA Non-recurring 4Q18 Adjusted effects / non-EBITDA cash(1) Price/Exchange Variation (1) Write-down of property, plant and equipment, provisions for ICMS tax credit losses, equity income, tax credits, reappraisal of biological assets and recovery of contingencies. 6 (7) 585 57 1,782 173 1,955 (274) 1,498 1,206 393 469 371 1,955 1,981 514 827 610

4Q18 Results Financial Income and Expenses 3Q18 4Q17 2017 Interest on financial investments 100 86 73 310 342 16% 37% -9% Financial Expenses (284) (308) (280) (1,129) (967) -8% 1% 17% Interest - loans and financing (foreign currency) (140) (148) (127) (540) (455) -5% 10% 19% Monetary and Exchange Variations 280 (444) (407) (1,744) (277) -163% -169% - Foreign Exchange Variations - Other (138) 49 68 141 (44) -382% -303% - Other Financial Income 15 12 14 56 77 25% 7% -27% (1) Change in the marked to market (4Q18: R$ 442 million | 3Q18: R$ 140 million | 4Q17: R$(195) million), added to received and paid adjustments. (2) Capitalized interest due to property, plant and equipment in progress. Interest income was R$100 million in 4Q18, up 16% from 3Q18, due to the higher basic interest rate in Brazil and higher yield from foreign currency accounts. Although the cash position at the end of the period, excluding the mark-to-market adjustment of hedge instruments, was 29% lower than in the previous quarter, the decrease occurred only towards the end of the quarter, mainly due to the payment of extraordinary dividends of R$2.8 billion. Compared to 4Q17, the 37% increase was due to the higher cash position in Brazil. Interest expenses on borrowings amounted to R$284 million in 4Q18, down R$24 million compared to 3Q18, mainly due to the lower gross debt and appreciation of the Brazilian real against the U.S. dollar, which decreased the recognition of interest owed on foreign-denominated debt, partially offset by the higher Libor rate. Compared to 4Q17, financial expenses remained stable. The effects of exchange variation on the debt balance positively impacted the Company’s results by R$418 million in the quarter, due to the 3% appreciation of the real against the dollar (4Q18: R$3.8748 | 3Q18: R$4.0039). The mark-to-market adjustment of derivative instruments on December 31, 2018 was positive at R$263 million, compared to an expense of R$178 million from the mark-to-market adjustment on September 30, 2018, representing a positive variation of R$441 million. Cash disbursement, which refers to the settlement of operations that matured during the period, was R$10 million on the debt hedge. The following table reflects the position of derivative hedging instruments at the end of December: 7 Other Financial Expenses (111) (79) (53) (312) (196) 41% 109% 59% Net Financial Result 432 (828) (781) (2,905) (783) -152% -155% - Other Financial Income / Expenses(2) (96) (67) (39) (256) (119) 43% 146% - Foreign Monetary and Exchange Variations - Debt 418 (493) (475) (1,885) (233) -185% -188% - Capitalized interest(2) 1 2 3 9 139 - - - Interest - loans and financing (local currency) (145) (162) (156) (598) (651) -10% -7% -8% Hedging(1) 432 (95) (128) (86) 238 - - - (R$ million) 4Q18 3Q18 4Q17 2018 2017 4Q18 vs 4Q18 vs 2018 vs Financial Income (including hedge result) 532 (9) (55) 224 580 - - -

4Q18 Results Sw aps Maturity US Dollar Fixed jan/35 $ 724 $ 757 R$246 R$140 Pay US Dollar CPI jan/35 $ 724 $ 757 R$ - R$ - Net Income (Loss) In 4Q18, the Company posted net income of R$1,525 million, compared to R$1,130 million in 3Q18 and R$280 million in 4Q17. The 35% increase compared to 3Q18 is mainly explained by exchange variation and the positive hedge result (negative result in the previous quarter), offset by the lower operating result, as explained previously. Compared to 4Q17, the increase is mainly due to the positive financial result. The following chart shows the main factors influencing net income (loss) in 4Q18, starting with Adjusted EBITDA in the same period: 8 Net (a+b+c+d)R$263 R$ (178) Embedded Derivatives Total (d)R$246 R$140 Notional (MM)Fair Value dec/18sep/18dec/18sep/18 Rec eive US Dollar Libor (1)-$- $-R$ - R$ - Brazilian Real CDI (2)aug/20R$86 R$86 R$88 R$87 Brazilian Real TJLP (3)-R$-R$-R$ - R$ - Brazilian Fixed (4)jul/19 R$39 R$56 R$39 R$54 Brazilian Real IPCA (5)sep/23R$ 1,028 R$ 1,028 R$ 1,187 R$ 1,105 Receive Total (a)R$ 1,314 R$ 1,246 Pay US Dollar Fixed (1)-$-$- R$ - R$ - US Dollar Fixed (2)aug/20$43 $171 R$ (170) R$ (174) US Dollar Fixed (3)-$-$- R$ - R$ - US Dollar Fixed (4) jul/19 $17 $ 32 R$(65) R$(95) Brazilian Real CDI (5)sep/23R$ 1,028 $ 1,028 R$ (1,054) R$ (1,033) Pay Total (b)R$ (1,289) R$ (1,302) Net (a+b)R$25 R$(56) Option US Dollar Options até 16M$ 3,035 $ 2,355 R$(8) R$ (262) Options Total (c)R$(8) R$ (262) Embedded Derivatives - Forestry Partnership and Standing Timber Supply Agreements Rec eive

4Q18 Results 4Q18 Net Income (R$ million) 432 (184) 418 1,955 1,525 4Q18 Adjusted EBITDA Debt Exchange Variation MtM hedge debt Net Interest Depreciation, amortization and depletion Income Taxes Other(1) 4Q18 Net Profit (Loss) (1)Includes other exchange variations and inflation adjustments, other financial income/expenses and other operating income/expenses. Debt Sep/18 Dec/17 Gross Debt R$ million 20,667 21,351 19,299 -3% 7% Gross Debt in US$(1) R$ million 12,407 13,309 11,347 -7% 9% Cost of debt (foreign currency) (2) % p.a. 4.5% 4.5% 4.5% 0.0 p.p. 0.0 p.p. Short-term debt % 15% 11% 5% 4 p.p. 10 p.p. Cash and market securities in US$ R$ million 1,598 3,554 3,583 -55% -55% Cash and cash Equivalents (3) R$ million 6,547 8,630 6,968 -24% -6% 0.2 -1.0 Net Debt/EBITDA (in US$) x 1.5 1.3 2.5 (1) Includes BRL to USD sw ap contracts. The original debt in dollars w as R$ 12,161 million (59% of the total debt) and debt in reais w as R$ 8,506 million (41% of the debt) (2 The costs are calculated considering the debt sw ap (3) Includes the f air value of derivative instruments (4) For covenant purposes Gross debt on December 31, 2018 was R$ 20,667 million, down R$ 684 million or 3% compared to the end of 3Q18. The following chart shows the changes in gross debt during the quarter: Gross Debt (R$ million) 236 21,351 284 10 20,667 Gross Debt Set/2018 Loans Principal Payment Interest Payment Interest Accrual Foreign Exchange Variation Others Gross Debt Dec/2018 9 (506)(290)(418) Net Debt/EBITDA (in US$)(4) x 1.4 1.2 2.4 0.2 -1.0 Net Debt R$ million 14,120 12,721 12,331 11% 15% Fair value of derivative instruments R$ million 263 (178) 134 -248% 96% Cash and market securities in R$ R$ million 4,686 5,254 3,251 -11% 44% Cost of debt (local currency) (2) % p.a. 8.4% 8.7% 8.2% -0.3 p.p. 0.2 p.p. Average maturity months 52 55 60 -3 -8 Gross Debt in R$ R$ million 8,260 8,042 7,952 3% 4% Unit Dec/18 Sep/18 Dec/17 Dec/18 vs Dec/18 vs (557) (131) (408)

4Q18 Results On December 31, the leverage ratio increased to 1.4x in USD and to 1.5x in BRL (vs. 1.2x in USD and 1.3x in BRL in 3Q18). The total average cost¹ of Fibria’s debt measured in USD was 4.2% p.a. (Sept/18: 3.9% p.a. | Dec/17: 3.4% p.a.), which is composed of the average cost of bank debt in local currency of 8.4% p.a. (Sept/18: 8.7% p.a. | Dec/17: 8.2% p.a.), which declined due to the drop in the future DI interest rate curve, and the cost in foreign currency of 4.5% p.a. (Sept/18: 4.5% p.a. | Dec/17: 4.5% p.a.). The following charts show Fibria’s debt by instrument, index and currency (including debt swaps): Gross Debt by Type Gross Debt by Index Gross Debt by Currency 7% 16% 23% 24% 21% 40% 60% 7% 14% 10% 36% 39% Pre-Payment Bond Finnvera ARC ACC BNDES NCE Others Libor TJLP Others Pre Fixed CDI Local currency Foreign currency (1)Total average cost, considering debt in reais adjusted by the market swap curve. The average term of total debt was 52 months in December 2018, compared to 55 months in September 2018 and 60 months in December 2017. The following chart shows the debt amortization schedule of Fibria’s total debt: Amortization Schedule (R$ million) 7,284 Revolver Cash on 2,722 2,633 1 hand 533 364 Liquidity 2019 2020 2021 2022 2023 2024 2025 2026 2027 (1)Not including the mark-to-market of hedge instruments. The balance of cash and cash equivalents on December 31, 2018 was R$6,547 million, including the R$263 million gain from the mark-to-market adjustment of hedge instruments. Excluding the effect of the mark-to-market adjustment of cash, 75% was invested in local currency, in government bonds and fixed-income instruments, while the balance was invested in short-term investments abroad. 10 1,000 3,076 2,863 3,006 6,284 1,448 2,094 1,905 1,892 1,985 2,499 2,473 383 2,661 1,651 390 1,628 1,515 741 443 1,784

4Q18 Results The Company has one untapped revolving credit facility in local currency in the amount of R$1,000 million, which is available until 2021, at a cost of CDI plus 2.5% p.a. when used (0.40% p.a. while on stand-by). This facility, although untapped, helps to improve the company’s liquidity conditions. As a result, the current cash position of R$6,547 million plus this line of R$1,000 million amounts to a readily available cash position of R$7,547 million. Accordingly, the ratio of cash (including the stand-by credit facility) to short-term debt stood at 2.5x on December 31, 2018. The following chart shows the evolution in Fibria’s net debt and leverage ratio since December 2017: Net debt / EBITDA (x) (R$) 2.5 2.1 1.8 1.5 (US$) 1.3 2.4 2.0 1.6 1.4 1.2 14,120 13,804 3,644 Dec/17 Mar/18 Jun/18 Sep/18 Dec/18 Net Debt (R$ million) Net Debt (US$ million) Capital Expenditure 3Q18 4Q17 2017 Forest Expansion - H2 Project - - 62 - - - 238 - Safety/Environment 28 17 16 70% 72% 66 48 38% Maintenance, IT, Modernization 175 128 129 37% 35% 566 484 17% IT 8 5 10 57% -23% 19 16 18% Subtotal Maintenance 803 704 582 14% 38% 2,667 2,062 29% Pulp logistics 150 35 18 - - 348 48 - Capex in the quarter totaled R$1,154 million, increasing 47% from 3Q18, mainly due to the acquisition of rural properties, increased expenses with logistics projects and higher investments in maintenance. Compared to 4Q17, the increase was due to higher expenses with maintenance, land acquisition and logistics projects, partially offset by lower expenses with the H2 Project. 11 Others 1 2 2 - -21% 4 5 -11% Total Capex 1,154 788 964 47% 20% 3,916 4,670 -16% Land acquisition 146 0 15 - - 574 18 - Modernization 22 13 14 71% 58% 61 99 -38% Maintenance 146 110 106 32% 38% 487 370 32% Forestry Renewal 600 560 436 7% 37% 2,034 1,529 33% Subtotal Expansion 54 47 348 16% -84% 322 2,538 -87% (R$ million) 4Q18 3Q18 4Q17 4Q18 vs 4Q18 vs 2018 2017 2018 vs Industrial Expansion - H2 Project 54 47 286 16% -81% 322 2,300 -86% 12,331 12,774 3,728 3,843 12,721 3,580 3,177

4Q18 Results Capital Markets Equity Average Daily Trading Volume (US$ million) Average Daily Shares Volume (million shares) 140 16 14 12 10 8 6 4 2 0 120 2.8 million shares 100 80 60 40 20 0 Oct-18 Nov-18 Dec-18 Oct-18 Nov-18 Dec-18 B3 NYSE B3 NYSE Average daily trading volume in Fibria stock in the quarter was approximately 2.8 million shares, up 5% from 3Q18. Average daily financial trading volume in the stock was US$50.2 million in 4Q18, down 3% from 3Q18, of which US$33.5 million was on the São Paulo Stock Exchange (B3) and US$16.7 million on the New York Stock Exchange (NYSE). Total Free Float (B3 + NYSE) Votorantim S.A. 162,974,335 29.43 Board of Directors, Fiscal Council and Executive Officers 51,064 0.01 Fore ign 54% m e s tic (Brazil) 46% TOTAL 553,733,881 100.00 On December 31, 2018, the Company's capital stock consisted of 553,733,881 common shares. The number of shares comprising free-float was 229,625,801 (41.47%), which are traded on the B3 and the NYSE, 54% of them held by foreign investors and 46% by local investors. Fibria’s market capitalization on December 31, 2018 was R$37.4 billion. Fixed Income Unit Dec/18 Sep/18 Dec/17 Sep/18 Dec/17 Fibria 2024 - Price USD/k 102.0 100.6 107.4 1% -5% Fibria 2025 - Price USD/k 94.7 92.7 - 2% - Fibria 2027 - Price USD/k 101.0 99.2 107.5 2% -6% 12 Treasury 10 y % 2.7 3.1 2.4 -0.4 p.p. 0.3 p.p. Fibria 2027 - Yield % 5.3 5.6 4.5 -0.3 p.p. 0.9 p.p. Fibria 2025 - Yield % 5.0 5.4 - -0.4 p.p. - Dec/18 vs Dec/18 vs Fibria 2024 - Yield % 4.8 5.1 3.9 -0.3 p.p. 0.9 p.p. Free Float 229,625,801 41.47 BNDESPar 161,082,681 29.09 Shareholders Structure Common Shares % Daily average 4Q18: Daily average 4Q18: US$50.2 million

4Q18 Results Appendix I – Gross Sales vs. Volume vs. Price Domestic Sales 164,118 191,783 414,155 488,135 2,524 2,545 (14.4) (15.2) (0.9) 663 644 3.1 Domestic Sales 164,118 184,160 414,155 324,510 2,524 1,762 (10.9) 27.6 43.2 663 542 22.3 Domestic Sales 703,845 662,010 1,637,097 1,025,783 2,326 1,549 6.3 59.6 50.1 636 485 31.2 13 Foreign sales 6,082,764 5,550,483 16,530,227 10,621,068 2,718 1,914 9.6 55.6 42.0 744 599 24.1 T otal 6,786,610 6,212,493 18,167,325 11,646,851 2,677 1,875 9.2 56.0 42.8 732 587 24.8 2018 vs 2017 Sales (T ons) Net Revenue (R$ 000) Avge Price (R$/T on) 2018 vs 2017 (%) Avge Price (US$/T on) 2018 vs 2017 (%) 2018 2017 2018 2017 2018 2017 T ons Revenue Avge Price 2018 2017 Avge Price Pulp Foreign Sales 1,275,450 1,712,410 3,575,909 3,700,105 2,804 2,161 (25.5) (3.4) 29.8 737 665 10.8 T otal 1,439,568 1,896,569 3,990,064 4,024,615 2,772 2,122 (24.1) (0.9) 30.6 728 653 11.5 4Q18 vs 4Q17 Sales (T ons) Net Revenue (R$ 000) Avge Price (R$/T on) 4Q18 vs 4Q17 (%) Avge Price (US$/T on) 4Q18 vs 4Q17 (%) 4Q18 4Q17 4Q18 4Q17 4Q18 4Q17 T ons Revenue Avge Price 4Q18 4Q17 Avge Price Pulp Foreign Sales 1,275,450 1,796,583 3,575,909 5,322,097 2,804 2,962 (29.0) (32.8) (5.4) 737 749 (1.6) T otal 1,439,568 1,988,366 3,990,064 5,810,232 2,772 2,922 (27.6) (31.3) (5.1) 728 739 (1.4) 4Q18 vs 3Q18 Sales (T ons) Net Revenue (R$ 000) Avge Price (R$/T on) 4Q18 vs 3Q18 (%) Avge Price (US$/T on) 4Q18 vs 3Q18 (%) 4Q18 3Q18 4Q18 3Q18 4Q18 3Q18 T ons Revenue Avge Price 4Q18 3Q18 Avge Price Pulp

4Q18 Results Appendix II – Income Statement Net Revenue 4,013 100% 5,836 100% 4,047 100% -31% -1% Foreign Sales 3,576 89% 5,322 91% 3,700 91% -33% -3% Cost related to production (1,842) -46% (2,466) -42% (2,167) -54% -25% -15% General and administrative (124) -3% (100) -2% (87) -2% 24% 43% Equity (0) 0% 0 0% 0 0% - - Current Income taxes expenses (822) -20% (19) 0% (265) -7% - - Net Income (Loss) attributable to controlling equity interest 1,524 38% 1,127 19% 278 7% 35% 448% Depreciation, amortization and depletion 557 14% 748 13% 687 17% -25% -19% Fair Value of Biological Assets 63 2% - 0% 103 3% - - Accruals for losses on ICMS credits 35 1% (0) 0% 38 1% - -8% (*) Calculation excludes pulp sales from agreement hith Klabin Net Revenue 18,264 100% 11,739 100% 56% Foreign Sales 16,530 91% 10,621 90% 56% Cost related to production (8,392) -46% (7,168) -61% 17% Selling and marketing (813) -4% (547) -5% 49% Financial Result (2,906) -16% (783) -7% 271% Other operating (expenses) income (434) -2% (340) -3% 28% Current Income taxes expenses (885) -5% (316) -3% 180% Net Income (Loss) attributable to controlling equity interest 3,052 17% 1,085 9% 181% Depreciation, amortization and depletion 2,637 14% 2,205 19% 20% Fair Value of Biological Assets (27) 0% 326 3% - Accruals for losses on ICMS credits 109 1% 114 1% -5% (*) Calculation excludes pulp sales from agreement with Klabin 14 EBIT DA margin pro-forma 9,547 58% 4,952 49% 93% Tax Incentive (2) 0% (5) 0% - EBIT DA adjusted 9,547 52% 4,952 42% 93% Property, Plant and Equipment disposal 108 1% (7) 0% - EBIT DA 9,358 51% 4,523 39% 107% Equity (1) 0% (0) 0% 0% Net Income (Loss) attributable to non-controlling equity interest 8 0% 8 0% -4% Deffered Income taxes expenses 129 1% (126) -1% - Net Income (Loss) 3,060 17% 1,093 9% 180% LAIR 3,816 21% 1,535 13% 148% Equity 1 0% 0 0% - General and administrative (392) -2% (286) -2% 37% Freight (1,513) -8% (1,081) -9% 40% Operating Profit 8,360 46% 3,491 30% 139% Cost of sales (9,904) -54% (8,248) -70% 20% Domestic Sales 1,734 9% 1,118 10% 55% Income Statement - Consolidated (R$ million) 2018 2017 2018 vs 2017 R$ AV% R$ AV% (%) EBIT DA margin pro-forma 1,955 54% 3,269 63% 1,981 57% -40% -1% Tax Credits/Reversal of provision for contingencies (0) 0% (0) 0% (0) 0% -4% - EBIT DA adjusted (*) 1,955 49% 3,269 56% 1,981 49% -40% -1% Fixed Assets disposals 75 2% 8 0% 34 1% 887% 124% EBIT DA 1,782 44% 3,262 56% 1,808 45% -45% -1% Equity 0 0% (0) 0% (0) 0% - - Net Income (Loss) attributable to non-controlling equity interest 1 0% 2 0% 2 0% -51% -34% Deffered Income taxes expenses 690 17% (538) -9% 205 5% - 237% Net Income (Loss) 1,525 38% 1,130 19% 280 7% 35% 444% Other operating (expenses) income (335) -8% (61) -1% (118) -3% 449% 185% Operating Income 1,656 41% 1,686 29% 340 8% -2% 387% Financial Result 432 11% (828) -14% (781) -19% - - Freight (312) -8% (463) -11% (370) -9% -33% -16% Operating Profit 1,859 46% 2,907 50% 1,510 37% -36% 23% Selling and marketing (175) -4% (231) -4% (185) -5% -25% -6% Cost of sales (2,154) -54% (2,929) -50% (2,537) -63% -26% -15% Domestic Sales 437 11% 514 9% 347 9% -15% 26% INCOME ST AT EMENT - CONSOLIDAT ED (R$ million) 4Q18 3Q18 4Q17 4Q18 vs 3Q18 4Q18 vs 4Q17 R$ AV% R$ AV% R$ AV% (%) (%)

4Q18 Results Appendix III – Balance Sheet Cash and cash equivalents 1,795 4,946 4,052 Short-term debt 3,076 2,286 1,693 Derivative instruments 211 79 124 Trade Accounts Payable 3,534 3,345 3,110 Inventories 4,008 2,948 2,080 Tax Liability 129 185 246 Others 211 278 188 Others 151 169 125 NON CURRENT 3,772 2,180 4,063 NON CURRENT 18,297 19,866 18,254 Derivative instruments 455 336 324 Accrued liabilities for legal proceedings 211 205 166 Recoverable taxes 1,224 569 1,868 Others 369 420 319 Others 437 318 311 Investments 200 188 153 Equity attributable to shareholders of the Company 14,149 16,137 14,577 Biological assets 4,580 4,472 4,253 Capital Reserve 14 20 13 Equity valuation adjustment 3,794 3,158 2,382 Equity attributable to non-controlling interests 74 75 73 15 T OT AL SHAREHOLDERS' EQUIT Y14,22316,21214,650 T OT AL ASSET S40,81942,69938,693 T OT AL LIABILIT IES40,81942,69938,693 Treasury stock-(19)(23) Intangible assets4,5394,5554,592 Statutory Reserve6123,2492,476 Property, plant & equipment , net15,59915,48315,102 Issued Share Capital9,7299,7299,729 Fostered advance662661645 Deferred income taxes821124753 Derivative instruments126176163 Marketable securities173170162 Long-term debt17,59119,06417,606 Recoverable taxes2611,730273 Dividends and Interest attributable to capital payable7316262 Trade accounts receivable, net1,3252,1461,193 Payroll and related charges402212202 Securities4,3163,6922,619 Derivative Instruments276418152 BALANCE SHEET (R$ million) ASSET SDec/18Sep/18Dec/17LIABILIT IESDec/18Sep/18Dec/17 CURRENT12,12815,82010,530 CURRENT8,2996,6215,790

4Q18 Results Appendix IV – Cash Flow Adjusted by (280) 444 407 1,745 277 (+) Foreign exchange losses, net 0 (0) (0) (1) (0) (+) Equity in losses of jointly-venture 75 8 15 108 (26) (+) (Gain)/loss on disposal of property, plant and equipment 284 308 280 1,128 967 (+) Interest expense 15 12 47 49 71 (+) Provisions and other Decrease (increase) in assets Inventories (818) (168) 48 (1,506) (108) Other assets/advances to suppliers (59) (96) (78) (127) (123) Trade payable 232 244 197 167 1,195 Payroll, profit sharing and related charges 190 58 15 200 34 Cash provided by operating activities Interest paid (290) (386) (301) (1,135) (1,046) Acquisition of property, plant and equipment and intangible assets and forests (1,124) (745) (949) (3,802) (4,636) Marketable securities, net (621) 409 866 (1,675) (745) Derivative transactions settled (10) (235) 67 (216) 122 Capital Increase (19) - - - Others - - - - - Borrowings 232 117 4,786 1,344 8,499 Dividends paid (2,786) (0) (0) (3,046) (395) Treasury 9 - - 11 - Effect of exchange rate changes on cash and cash equivalents (128) 124 82 292 (15) Cash and cash equivalents at beginning of year 4,946 3,283 2,845 4,052 2,660 16 Cash and cash equivalents at end of year 1,795 4,946 4,052 1,795 4,052 Net increase (decrease) in cash and cash equivalents (3,151) 1,663 1,207 (2,257) 1,392 Other (2) 1 4 4 10 NET CASH USED IN FINANCING ACT IVIT IES (3,053) (103) (235) (3,609) 2,387 Repurchase of shares - - - - (17) Repayments - principal amount (506) (221) (5,024) (1,922) (5,710) NET CASH USED IN INVEST ING ACT IVIT IES (1,802) (606) (28) (5,813) (5,086) Cash flows from financing activities Proceeds from sale of investment - Losango Project - - - - 202 Acquisition of interest in subsidary - - - - (19) Proceeds from sale of property, plant and equipment 2 8 3 16 27 Advances for acquisition of timber from forestry partnership program (30) (42) (15) (114) (36) Income taxes paid (10) (39) (9) (68) (36) NET CASH PROVIDED BY OPERAT ING ACT IVIT IES 1,832 2,247 1,387 6,874 4,106 Cash flows from investing activities Interest received 72 43 46 194 275 Other payable (32) (13) (0) 30 50 Taxes payable (855) 56 (167) (880) (200) Increase (decrease) in liabilities Recoverable taxes 782 (84) 6 564 (386) Trade accounts receivable 725 (609) (358) 13 (513) (+) Program Stock Options (4) 0 1 (3) 3 (+) Impairment of recoverable ICMS 35 (0) 38 109 114 (+) Interest and gain and losses in marketable securities (78) (59) (55) (226) (273) (+) Fair value of biological assets 63 - 103 (27) 326 (+) Change in fair value of derivative financial instruments (432) 95 128 87 (238) (+) Depreciation, depletion and amortization 557 748 687 2,637 2,205 INCOME (LOSS) BEFORE T AXES ON INCOME 1,656 1,686 340 3,816 1,535 UNAUDIT ED CONSOLIDAT ED ST AT EMENT OF CASH FLOW (R$ million) 4Q18 3Q18 4Q17 2018 2017

4Q18 Results Appendix V – Breakdown of EBITDA and Adjusted EBITDA (CVM Instruction 527/2012) (+/-) Financial results, net (432) 828 781 (+) Depreciation, amortization and depletion 557 748 687 (+) Equity 0 (0) (0) (+/-) Loss (gain) on disposal of property, plant and equipment 75 8 34 (-) Tax credits/reversal of provision for contingencies (0) (0) (0) EBITDA is not a standard measure established by Brazilian or international accounting rules and represents earnings (losses) in the period before interest, income tax and social contribution, depreciation, amortization and depletion. The Company presents adjusted EBITDA in accordance with CVM Instruction 527, of October 4, 2012, adding or subtracting from this amount equity income, provisions for losses on recoverable ICMS, gains (losses) from write-offs of fixed assets, the fair value of biological assets and tax credits/reversal of provision for contingencies, in order to provide better information on its ability to generate cash, pay debt and sustain its investments. Neither measurement should be considered as an alternative to the Company’s operating income and cash flows or as an indicator of liquidity for the periods presented. 17 EBITDA Adjusted 1,955 3,269 1,981 (+) Accrual for losses on ICMS credits 35 (0) 38 (-) Fair Value of Biological Assets 63 - 103 EBITDA 1,782 3,262 1,808 (+) Taxes on income 131 557 60 Adjusted EBITDA (R$ million) 4Q18 3Q18 4Q17 Income (loss) of the period 1,525 1,130 280

4Q18 Results Appendix VI – Financial and Operating Data 3Q18 4Q17 Closing 3.8748 4.0039 3.8558 3.3080 -3% 17% Pulp net revenues distribution, by region 4Q18 3Q18 4Q17 2018 3Q18 4Q17 3Q18 4Q17 PIX Europe 1,045 1,050 940 0% 11% 1,037 18 PIX China 742 770 723 -4% 3% 760 Pulp price - FOEX BHKP (US$/t) 4Q18 3Q18 4Q17 4Q18 vs 4Q18 vs 2018 4Q18 vs4Q18 vs Europe 37% 32% 28% 5 p.p. 9 p.p. 33% North America 27% 14% 20% 13 p.p. 7 p.p. 17% Asia 25% 45% 43% -20 p.p. -18 p.p. 40% Brazil / Others 11% 9% 9% 2 p.p. 2 p.p. 9% Average 3.8049 3.9533 3.6046 3.2474 -4% 17% Exchange Rate (R$/US$) 4Q18 3Q18 2Q18 4Q17 4Q18 vs 4Q18 vs

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

Date: February 21, 2019

	Fibria Celulose S.A.

	By:	/s/ Marcelo Feriozzi Bacci
	Name:	Marcelo Feriozzi Bacci
	Title:	Chief Financial Officer and Investor Relations Director

Fibria Celulose S.A. 6-K