Ero Copper Corp. (TSX: ERO) (NYSE: ERO) is pleased to announce the remaining assay results from its 28,000-meter Phase 1 drill program at the Furnas Copper-Gold Project located in the Carajás Mineral Province in Pará State, Brazil.

Complete results from the Phase 1 program are highlighted by intercepts that continue to demonstrate high-grade continuity throughout the deposit as well as significantly extend the known limits of mineralization within the high-grade zones (greater than 1% CuEq¹) to depth. To date, mineralization has been extended to a depth of approximately 950 meters down-dip from surface and remains open.

New Phase 1 program drill results are highlighted by:

• FURN-DD-00322: 115 meters at 0.76% copper and 0.47 grams per tonne (“gpt”) gold (0.98% CuEq¹), including 46 meters at 0.81% copper and 0.56 gpt gold (1.11% CuEq¹) and 28 meters at 0.91% copper and 0.71 gpt gold (1.25% CuEq¹). This is the deepest hole drilled to date in the Southeast zone, drilled approximately 220 meters down-dip from the previously known extent of mineralization and 950 meters down-dip from surface.

• FURN-DD-00305: 103 meters at 0.88% copper and 0.80 gpt gold (1.26% CuEq¹), including 27 meters at 1.04% copper and 1.18 gpt gold (1.60% CuEq¹), demonstrating continuity of known mineralization within the high-grade envelope of the Southeast zone and supporting conversion of the current mineral resource.

• FURN-DD-00321: 115 meters at 0.47% copper and 0.27 gpt gold (0.60% CuEq¹), including 8 meters at 1.13% copper and 0.49 gpt gold (1.36% CuEq¹), the deepest hole drilled in the Northwest zone, approximately 650 meters down-dip from surface, demonstrating further down-dip potential in the Northwest zone, which has had limited extensional drilling to date in comparison to the Southeast zone.

• FURN-DD-00300: 80 meters at 1.02% copper and 0.36 gpt gold (1.19% CuEq¹), including 28 meters at 1.67% copper and 0.49 gpt gold (1.90% CuEq¹), demonstrating continuity within the high-grade envelope of the Northwest zone and supporting conversion of the current mineral resource.

1. ^{Where applicable, copper equivalent (“CuEq”) in this press release has been calculated using the following formula: Cu grade + (Au grade x 0.03215 x ($1,900 gold price x 61.50% gold metallurgical recovery / (0.01 x $9,259/tonne copper price x 85.00% copper metallurgical recovery)).}

Step-out drilling during the Phase 1 program has now extended the known limits of mineralization to a depth of approximately 950 meters down-dip from surface. The National Instrument 43-101 compliant mineral resource estimate for the Project is based on an average historical depth of drilling of 300 meters (vertical), with a maximum localized down-dip depth from surface of 580 meters. For additional information on the Project’s last published mineral resource estimate, please refer to the Company’s press release dated October 2, 2024.

Drilling at Furnas continues with eight drill rigs currently on site. Ero expects to complete the 17,000-meter Phase 2 drill program in early Q4 2025, approximately three months ahead of schedule.

“The full results from the 28,000-meter Phase 1 drill program are highly encouraging and reinforce the potential for Furnas to be a large-scale, long-life, high-grade copper and gold mining operation that we believe will fundamentally transform the Company and add considerable value for our partner, Vale Base Metals” said Makko DeFilippo, President and Chief Executive Officer. “The Phase 1 program has not only confirmed continuity of high- grade mineralization, but also exceeded our expectations in demonstrating high-grade mineralization well beyond the down-dip limits of the last published mineral resource estimate.”

“This year, the majority of our exploration efforts have been dedicated to advancing Furnas as the next leg of our growth strategy. Following the cumulative 45,000-meter Phase 1 and 2 drill programs, and with eight drill rigs currently on site to support the Phase 3 program and ongoing engineering studies, we are well-positioned to continue building momentum.”

The complete results from the Phase 1 drill program will serve as the foundation for an updated NI 43-101 compliant mineral resource estimate as well as a preliminary economic assessment (“PEA”) of the Project. The PEA, which was initiated earlier this year, remains on track for completion during the first half of 2026. Please refer to the Company’s July 10, 2025 press release in conjunction with the current release for complete results of the Phase 1 program.

ABOUT THE FURNAS COPPER-GOLD PROJECT

Furnas is an iron oxide copper-gold deposit located approximately 50 kilometers southeast of Vale Base Metal’s Salobo operations and approximately 190 kilometers northeast of Ero’s Tucumã Operation. Covering an area of approximately 2,400 hectares, the Project sits within fifteen kilometers of extensive regional infrastructure, including paved roads, an industrial-scale cement plant, a power substation and Vale S.A.’s railroad loadout facility.

In July 2024, the Company signed a definitive earn-in agreement with Salobo Metais S.A, a subsidiary of VBM, to earn a 60% interest in the Project upon completion of several exploration, engineering and development milestones over a five-year period. In exchange for its 60% interest, Ero will solely fund a phased work program during the earn-in period and grant VBM up to an 11.0% “free carry” on future Project construction capital expenditures. For additional details on the key terms and execution of the Agreement, please refer to the Company’s press releases dated October 30, 2023 and July 22, 2024.

Prior to the commencement of the Phase 1 drill program, the Company published an initial NI 43-101 compliant mineral resource estimate on the Project, based on approximately 90,000 meters of historical drilling. This estimate underscored the significant potential of the Project. Using a 1.00% copper equivalent cut-off grade, the mineral resource estimate, effective June 30, 2024, totaled:

• Indicated Mineral Resource: 35.2 million tonnes grading 1.04% copper and 0.69 gpt gold (1.36% CuEq¹), containing an estimated 364,700 tonnes of copper and 775,300 ounces of gold
• Inferred Mineral Resource: 61.3 million tonnes grading 1.06% copper and 0.63 gpt gold (1.36% CuEq¹), containing an estimated 647,400 tonnes of copper and 1,235,600 ounces of gold

For additional information on the Project’s mineral resource estimate, please see the Company’s press release dated October 2, 2024 as well as the corresponding technical report titled “Furnas Copper Project – Para State, Brazil – NI 43-101 Mineral Resource Estimate Technical Report”, dated November 18, 2024 with an effective date of June 30, 2024, prepared for the Company by Anderson Gonçalves Candido, FAusIMM of RPMGlobal Canada Limited (“RPM”).

1. ^{Where applicable, copper equivalent (“CuEq”) in this press release has been calculated using the following formula: Cu grade + (Au grade x 0.03215 x ($1,900 gold price x 61.50% gold metallurgical recovery / (0.01 x $9,259/tonne copper price x 85.00% copper metallurgical recovery)).}

Figure 1: Furnas Plan View Map, including drill collar locations. Rock types include:

Figure 2: Cross section within the high-grade SE Zone of Furnas. Rock types include:

Figure 3: Cross section within the high-grade NW Zone of Furnas. Rock types include:

DRILL RESULTS – SOUTHEAST ZONE

DRILL RESULTS – NORTHWEST ZONE

DRILL HOLE INFORMATION – SOUTHEAST ZONE

DRILL HOLE INFORMATION – NORTHWEST ZONE

NOTE ON NI 43-101 COMPLIANT TECHNICAL REPORT

The conversion of drill results presented in this press release into NI 43-101 compliant mineral resources or mineral reserves requires additional work and analysis that remains ongoing. Additional drilling and technical work are required to determine whether the results related to down-dip intercepts will be included in future NI 43-101 compliant mineral resource or reserve estimates.

QUALIFIED PERSON

Mr. Cid Gonçalves Monteiro Filho, SME RM (04317974), MAIG (No. 8444), FAusIMM (No. 329148) of Ero Copper, a Qualified Person as defined in NI 43-101, has reviewed this press release on behalf of the Company and has approved the scientific and technical information contained in this press release.

QUALITY ASSURANCE & QUALITY CONTROL

Current QA/QC Program

At the Project, the Company is currently drilling with third-party contracted core drill rigs, operated by Major Drilling Group International Inc. and Drillgeo Geologia e Sondagem Ltda. – independent contractors engaged since October 2024. Drill core is logged, photographed and split in half using a diamond core saw at the Company’s core logging and storage facilities. Half of the drill core is retained on site and the other half-core is used for analysis, with samples collected at a minimum of 1.5 meters and a maximum of 2.5 meters with an average length of 2.0 meters. Sampling commences at least 3.0 meters before the start of the mineralized zone and continues at least 3.0 meters beyond the limit of the mineralized zone. Sample collection is performed at the Company’s logging facilities with all sample preparation performed at ALS Brasil Ltda.’s laboratory, located in Parauapebas (PA), Brazil, who is independent of the Company. Samples are analyzed by the certified laboratory of ALS Peru S.A., who is independent of the Company. Copper content is determined by four-acid digestion followed by ICP-MS analysis, while gold content is analyzed using fire assay with ICP-AES. When copper grades exceed 1%, Atomic Absorption Spectroscopy is used to determine it. All sample results from the Phase 1 drill program have been monitored through a quality assurance and quality control program that includes adherence to the internal operational procedures and the insertion of certified standards, blanks and duplicates at a rate of three standards, one coarse blank, one fine blank, one field duplicate, one coarse duplicate, and one pulp duplicate for every 50 total samples, yielding a blended QC rate of approximately 16%.

QA/QC Validation

The QA/QC validation process undertaken for the Phase 1 drill program of the Project is consistent with the process set out in the NI 43-101 technical report with respect to Furnas , titled “Furnas Copper Project – Para State, Brazil – NI 43-101 Mineral Resource Estimate Technical Report”, dated November 18, 2024 with an effective date of June 30, 2024 and Ero’s internal guidelines and best practices.

NOTES ON MINERAL RESOURCES

The Canadian Institute of Mining, Metallurgy and Petroleum Definition Standards (2014) were used for reporting the Project’s mineral resource estimate, which is effective as at June 30, 2024 and presented on a 100% ownership basis. All figures have been rounded to the relative accuracy of the estimates. Summed amounts may not add due to rounding. Mineral resources that are not mineral reserves do not have a demonstrated economic viability.

Mr. Anderson Gonçalves Candido, FAusIMM of RPM completed a review of the mineral resource estimate using an appropriate validation process. The mineral resource estimate process was also supervised and reviewed by Mr. Cid Gonçalves Monteiro Filho, SME RM (04317974), MAIG (No. 8444), FAusIMM (No. 329148) who is the Manager, Resources & Reserves of the Company and a “qualified person” within the meanings of NI 43-101.

Mineral resources have been estimated using a copper price of US$9,259/tonne, a gold price of US$1,900/oz, a USD:BRL foreign exchange rate of 5.10, and copper and gold metallurgical recovery rates of 85.00% and 61.50%, respectively. The estimation was constrained using Datamine’s Mineable Shape Optimizer (“MSO”) at a 0.55% break-even copper cut-off grade. Mineral resources were estimated using ordinary kriging within a 25-meter by 25-meter by 4- meter block size (X, Y, Z), with a minimum sub-block size of 6.25 meters by 6.25 meters by
2.0 meters.

ABOUT ERO COPPER CORP

Ero Copper is a high-margin, high-growth copper producer with operations in Brazil and corporate headquarters in Vancouver, B.C. The Company’s primary asset is a 99.6% interest in the Brazilian copper mining company, Mineração Caraíba S.A. owner of the Company’s Caraíba Operations, which are located in the Curaçá Valley, Bahia State, Brazil, and the Tucumã Operation, an open pit copper mine located in Pará State, Brazil. The Company also owns 97.6% of NX Gold S.A. which owns the Xavantina Operations, an operating gold mine located in Mato Grosso State, Brazil. In July 2024, the Company signed a definitive earn-in agreement with Vale Base Metals for the right to acquire a 60% interest in the Furnas Copper-Gold Project, located in the Carajás Mineral Province in Pará State, Brazil. For more information on the earn-in agreement, please see the Company’s press releases dated October 30, 2023 and July 22, 2024. Additional information on the Company and its operations, including technical reports on the Caraíba Operations, Xavantina Operations, Tucumã Operation and the Furnas Copper-Gold Project, can be found on the Company’s website (www.erocopper.com), on SEDAR+ (http://www.sedarplus.ca/landingpage/) and on EDGAR (www.sec.gov).