Ero Copper Corp. (TSX: ERO) (NYSE: ERO) is pleased to announce assay results on an additional 24,000 meters of exploration drilling performed subsequent to the Phase 1 program at the Furnas Copper-Gold Project, located in the Carajás Mineral Province in Pará State, Brazil. The Company has completed over 75,000 meters of drilling through the end of May 2026, with assay results currently available for approximately 52,000 meters. There are ten drill rigs operating at the Project, and the deposit remains open to depth and along strike.

Assay results from the ongoing drill programs are highlighted by significant step-out drill results occurring along strike and to depth:

• FURN-DD-00357: 90 meters at 0.74% copper, 0.50 grams per tonne gold and 3.18 gpt silver (1.13% CuEq¹), including 32 meters at 1.17% copper, 0.68 gpt gold and 5.40 gpt silver (1.70% CuEq¹), a step-out hole in the SE zone, extending the known limits of mineralization by approximately 115 meters down-dip, demonstrating potential for additional high-grade extensions within the SE zone.
• FURN-DD-00354: 45 meters at 0.98% copper, 0.36 gpt gold and 1.72 gpt silver (1.25% CuEq¹), including 20 meters at 1.78% copper, 0.25 gpt gold and 3.12 gpt silver (1.98% CuEq¹), representing a high-grade step-out intercept in the SE zone approximately 80 meters beyond the limit of the inferred mineral resource.
• FURN-DD-00368: 41 meters at 0.94% copper, 0.44 gpt gold and 1.58 gpt silver (1.28% CuEq¹), including 16 meters at 0.87% copper, 0.89 gpt gold and 1.52 gpt silver (1.53% CuEq¹), drilled in the Central zone of the Project, approximately 220 meters down-dip of the inferred mineral resource estimate and more than 1.1 kilometers west of the high-grade resource of the SE zone, highlighting a new zone of exploration potential between the established SE and NW zones.

And by high-grade infill results within the primary SE and NW mineralized zones:

• FURN-DD-00340: 88 meters at 0.81% copper, 0.61 gpt gold and 3.75 gpt silver (1.29% CuEq¹), including 27 meters at 1.25% copper, 0.77 gpt gold and 6.06 gpt silver (1.86% CuEq¹), demonstrating high-grade continuity over significant thicknesses within the SE zone, supporting the ongoing resource conversion drill program.
• FURN-DD-00348: 65 meters at 0.65% copper, 0.42 gpt gold and 1.30 gpt silver (0.97% CuEq¹), including 26 meters at 0.78% copper, 0.42 gpt gold and 1.30 gpt silver (1.18% CuEq¹) and 12 meters at 0.67% copper, 0.65 gpt gold and 2.12 gpt silver (1.60% CuEq¹), drilled at the northwestern edge of the NW zone mineral resource, supporting future resource growth potential. The hole also returned a shallower intercept of 15 meters at 2.97% copper and 11.81 gpt silver (3.05% CuEq¹).

WORK PROGRAM HIGHLIGHTS

• Drilling continues to demonstrate high-grade continuity within the NW and SE zones and extend mineralization both to depth and strike adjacent to planned underground infrastructure of the Preliminary Economic Assessment (“PEA”)² mine plan. The most recent set of assay results include approximately 6,000 meters of infill drilling targeting conversion of inferred mineral resources to at least indicated mineral resources in support of future engineering studies.
• The Company remains on track to complete the three contractual drilling programs under the Furnas earn-in agreement by year-end, approximately 2 years ahead of the required schedule for the drilling milestones. Pursuant to the agreement, the Company will earn a 60% interest in the Project upon completion of these drill programs and prescribed engineering work programs.³
• In parallel, the Company is well-advanced across additional technical work streams including permitting, confirmatory metallurgical testwork, advanced geotechnical drilling, hydrogeological studies and ongoing environmental baseline studies in support of a Pre-Feasibility Study (“PFS”) expected to be published in 2027.
• The Company expects to award the engineering contract for the PFS and Feasibility Study (“FS”) in mid-2026.
• In addition, value-enhancement opportunities identified in the PEA continue to be evaluated, including magnetic separation of tailings to produce a high-grade magnetite (iron) concentrate and a gravity circuit to improve gold recoveries.

“Every drill result from Furnas reinforces the scale, quality and growth potential of the deposit,” said Makko DeFilippo, President and Chief Executive Officer. “High-grade continuity within the SE and NW zones remains strong, and new step-out drilling in the Central zone, near planned infrastructure, highlights new opportunities to build upon an already compelling PEA mine plan.

“We are advancing Furnas on multiple fronts, with ten drill rigs operating on site and permitting, engineering and environmental workstreams progressing toward a PFS. Together with Vale Base Metals⁴, we remain focused on de-risking the Project and positioning Furnas as a cornerstone of Ero’s long-term organic growth strategy.”

1. Where applicable, copper equivalent in this press release has been calculated using the following formula: Cu grade + ((Au grade × 0.03215 × US$2,500 gold price × 74.6% gold metallurgical recovery) + (Ag grade × 0.03215 × US$24.00 silver price × 71.0% silver metallurgical recovery)) / (0.01 × US$9,038.94/tonne copper price × 90.3% copper metallurgical recovery).
2. For more information on the updated Furnas mineral resource estimate and inaugural PEA, please see the Company’s press release dated February 23, 2026 and the 2026 Technical Report (as defined below).
3. For more information on the Company’s plans to earn a 60% interest in the Furnas Copper-Gold Project, please see its press releases dated October 30, 2023 and July 22, 2024.
4. “Vale Base Metals” includes Vale Base Metals Limited and its subsidiaries.

Environmental Studies in Support of Project Permitting Advancing

Baseline environmental studies commenced in Q1 2024, building on historical environmental work conducted by Vale Base Metals. The Company plans to submit an application for a Preliminary License by year-end 2026, following the expected completion of an Environmental Impact Assessment and Environmental Impact Report. Mining projects in Brazil require a three-phase licensing process, in parallel with the federal mining-title process administered by the National Mining Agency:

• Phase 1 – Preliminary License: Confirms environmental feasibility and approves the Project’s location and basic design concept, following review of the EIA/RIMA and applicable public consultation requirements.
• Phase 2 – Installation License: Authorizes construction and installation in accordance with approved engineering plans and environmental control programs, subject to compliance with Preliminary License conditions.
• Phase 3 – Operating License: Authorizes operations after construction is complete, required environmental controls are implemented and applicable environmental, mining and other regulatory conditions have been satisfied.

Key environmental authorizations secured to date at Furnas include vegetation clearance, wildlife management, a water use permit for exploration and additional water-take authorization.

Metallurgical Testwork Continues to Validate PEA Assumptions; Moving Forward with Evaluation of Value-Enhancement Opportunities

Metallurgical testwork completed since the publication of the PEA includes seven additional variability tests, 24 additional locked-cycle flotation tests, and a continuous mini pilot plant test. Results continue to support the proposed metallurgical process flowsheet outlined in the PEA and validate recoveries for copper, gold and silver as well as concentrate quality parameters. Additional pilot plant variability tests will be performed in H2 2026 in support of the PFS.

Additional testwork continues to show that magnetic separation of flotation tailings offers the potential to produce a high-grade magnetite concentrate while also reducing tailings mass, representing a significant value-enhancement opportunity for the Project in future studies.

Drill Results Continue to Demonstrate High-Grade Continuity and Extend Mineralization

Drill results in this update include approximately 24,000 meters of drilling comprised of 6,000 meters of infill drilling and approximately 18,000 meters of resource extension drilling. Infill drilling was designed to target upgrades of inferred mineral resources to higher-confidence categories, while resource expansion drilling focused on demonstrating extensions at depth and along strike, including opportunities within the under-explored Central zone between the well established NW and SE mineralized corridors.

ABOUT THE FURNAS COPPER-GOLD PROJECT

Furnas is an iron oxide copper-gold deposit located approximately 70 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.⁵, 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.

The Company published a PEA on the Project on March 30, 2026 with an effective date of February 23, 2026, highlighting an initial 24-year mine life with LOM average annual production of 81 kt CuEq¹ with average annual production of 108 kt CuEq¹ over the first 15 years of mine life. The PEA is supported by an updated mineral resource estimate, with an effective date of November 30, 2025, that incorporates approximately 90,000 meters of historical drilling completed by Vale S.A. and Anglo American plc, together with 28,000 meters of Phase 1 drilling completed by the Company through July 2025.

For additional information on the PEA and the Project’s mineral resource estimate, please see the Company’s press release dated February 23, 2026 as well as the corresponding technical report titled “Preliminary Economic Assessment for the Furnas Project – Pará State, Brazil – NI 43-101 Technical Report”, dated March 30, 2026 with an effective date of February 23, 2026 (the “2026 Technical Report”), which is available under the Company’s profile on SEDAR+ (www.sedarplus.com), on EDGAR (www.sec.gov) and on the Company’s website (www.ero.com).

The PEA is preliminary in nature and includes inferred mineral resources, which are considered too speculative geologically to have the economic considerations applied to them that would enable them to be categorized as mineral reserves, and there is no certainty that the PEA will be realized. Mineral resources that are not mineral reserves do not have demonstrated economic viability.

1. Where applicable, copper equivalent in this press release has been calculated using the following formula: Cu grade + ((Au grade × 0.03215 × US$2,500 gold price × 74.6% gold metallurgical recovery) + (Ag grade × 0.03215 × US$24.00 silver price × 71.0% silver metallurgical recovery)) / (0.01 × US$9,038.94/tonne copper price × 90.3% copper metallurgical recovery).

1. Salobo Metais S.A., is a wholly owned subsidiary of Vale Base Metals Limited. Vale Base Metals Limited is 90% indirectly owned by Vale, and 10% indirectly owned by Manara Minerals Investment Company (Manara Minerals).

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

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

 Figure 3: Geologic cross section within the high-grade Central Zone of Furnas. Rock types include:

 Figure 4: Geologic cross section within the high-grade NW Zone of Furnas. Rock types include:

 Figure 5: Furnas SE zone drill hole collars plotted in plan view of the PEA block model and planned mine infrastructure. Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability.

 Figure 6: Furnas SE zone new drill hole collars plotted in long section view of the PEA block model and planned mine infrastructure. Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability.

 Figure 7: Furnas NW zone drill hole collars plotted in plan view of the PEA block model and planned mine infrastructure. Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability.

Figure 8: Furnas NW zone new drill hole collars plotted in long section of the PEA block model and planned mine infrastructure. Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability.

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 drill results disclosed in this press release are not incorporated in the mineral resource estimate underpinning 2026 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 these results, including down-dip intercepts, will be included in an NI 43-101 technical report associated with the PFS.

QUALIFIED PERSON

Mr. Cid Gonçalves Monteiro Filho, SME RM (04317974), MAIG (No. 8444), FAusIMM (No. 329148) has reviewed, verified and approved the scientific and technical information contained in this press release. Mr. Monteiro is Manager, Resources & Reserves of the Company and is a “qualified person” within the meanings of NI 43-101.

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 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. Samples are collected at the Company’s logging facilities, and all sample preparation is performed at ALS Brasil Ltda.’s laboratory in Parauapebas (PA), Brazil, which is independent of the Company. Samples are analyzed by the certified laboratory of ALS Peru S.A., which 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 them. All sample results from the Phase 1 drill program (28,000 meters, drilling completed through July 2025), the Phase 2 drill program (17,000 meters, drilling completed in Q4 2025) and the analytical results received to date from the Phase 3 drill program (approximately 30,000 meters, drilling completed in May 2026) have been monitored through a quality assurance and quality control (“QA/QC”) 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, Phase 2 and Phase 3 drill programs of the Project is consistent with the process set out in the 2026 Technical Report and in the previous NI 43-101 technical report with respect to Furnas, titled “Furnas Copper Project – Pará State, Brazil – NI 43-101 Mineral Resource Estimate Technical Report”, dated November 18, 2024 with an effective date of June 30, 2024 (the “2024 Technical Report”), and is consistent with Ero’s internal guidelines and best practices.

For details on the post-mortem QA/QC program performed by the Company on historic drilling completed by Vale S.A. and Anglo American plc, please refer to the Company’s press release dated October 2, 2024 and to the 2024 Technical Report.

ABOUT ERO

Ero is a Brazil-focused, growth-oriented mining company with a diversified portfolio of copper and gold assets. Headquartered in Vancouver, B.C., the Company operates two copper mines – the Caraíba Operations in Bahia State and the Tucumã Operation in Pará State – as well as the Xavantina Operations, a producing gold mine in Mato Grosso State. In addition to its operating assets, Ero is advancing the Furnas Copper-Gold Project, located in the mineral-rich Carajás Province in Pará State, through a definitive earn-in agreement with Vale Base Metals to acquire a 60% interest in the project.

Ero’s operating philosophy is grounded in a commitment to safety, operational excellence, and the responsible production of minerals essential for a better tomorrow.