Top Sustainability Consulting Firms

Executive overview

Sustainability consulting has evolved from a niche advisory service into a mainstream strategic and technical discipline, spanning net‑zero strategy, ESG integration, climate risk, nature and biodiversity, circularity, and regulatory compliance (CSRD, ISSB, SEC climate, BRSR, etc.). The market today is led by a mix of global pure‑play sustainability specialists, environmental and engineering consultancies, and Big Four/strategy firms with dedicated sustainability and climate practices.

Across rankings and analyst quadrants, firms such as ERM, Anthesis Group, McKinsey & Company (McKinsey Sustainability), Deloitte, EY, PwC, KPMG, WSP, AECOM, South Pole, Accenture, Boston Consulting Group (BCG), Bain & Company, Systemiq, Roland Berger, and Oliver Wyman repeatedly appear as leaders in sustainability and climate consulting. This report applies OneStopESG’s listicle template to synthesize how these ten firms compare, what they do well, and which types of clients and use cases they are best suited for.

What sustainability consulting firms do?

Sustainability consulting firms help organizations translate climate, ESG, and broader sustainability pressures into strategies, roadmaps, and operational changes. Services typically include climate and net‑zero strategy, ESG and sustainability reporting, decarbonization plans, circular economy and resource efficiency, climate‑risk and resilience assessments, sustainable finance, and stakeholder engagement.

These firms are critical for:

• Interpreting complex and evolving regulations (CSRD/ESRS, ISSB, SEC, EU Taxonomy, BRSR, etc.).
• Designing credible transition plans aligned with SBTi and net‑zero commitments.
• Integrating sustainability into core business strategy, capex decisions, M&A, and product design.

For boards, CFOs, and CSOs, the choice of sustainability consulting partner shapes the credibility and speed of their transition.

Quick comparison of sustainability consulting firms

High‑level firm comparison

How the firms were selected

This list focuses on global sustainability consulting firms with strong recognition in independent rankings and broad service offerings across ESG, climate, and environmental topics. It draws on:

• Rankings of top sustainable consulting firms and environmental & sustainability consultancies, which highlight ERM, WSP, AECOM, Anthesis, and other engineering‑environment leaders.
• Analyst reports and quadrants for climate and ESG consulting, where Deloitte, EY, KPMG, PwC, ERM, and WSP appear as leaders.
• Articles and profiles of mid‑sized sustainability specialists such as Anthesis and South Pole, which are repeatedly cited as go‑to pure‑play sustainability partners.
• Technical depth and domain expertise. We prioritised firms with dedicated sustainability teams and scientific capabilities. Examples include WSP's 25,000 Earth and Environment specialists and ERM's exclusive focus on sustainability.
• Execution and change management track record. We considered the ability to integrate ESG into core operations, drive adoption and create long-term value, not just produce strategy documents.

The final 16 reflect a balance between pure‑play sustainability firms, engineering‑led environmental consultancies, and global professional‑services networks.

Top sustainability consulting firms

1. ERM (Environmental Resources Management)

ERM is widely described as the world’s largest pure‑play sustainability consultancy, with more than 6,000 employees and over 160 offices globally. It provides environmental, health, safety (EHS), risk, social, climate, and ESG advisory across high‑impact sectors such as energy, chemicals, pharma, and infrastructure.

Key features:

• End‑to‑end sustainability services covering corporate sustainability and climate change, EHS compliance, low‑carbon transition, ESG strategy, and digital solutions.
• Strong technical depth in environmental and social impact assessment, remediation, and operational risk.
• Growing focus on net‑zero, just transition, and sustainable finance, including M&A due diligence and portfolio decarbonization.

Industries served:

• Energy, mining, chemicals, manufacturing, infrastructure, and life sciences.
• Financial sponsors and PE funds investing in high‑impact sectors.

Pros:

• Pure‑play focus ensures sustainability is core business, not an adjacent service.
• Combination of technical EHS capabilities and strategic ESG advisory.

Cons:

• Strongest fit is for asset‑intensive sectors; digital‑native or small companies may find the footprint heavy.
• Like many global firms, regional team quality and specialization can vary.

Best for: Large, asset‑heavy organizations needing deep technical and strategic support to manage environmental risk and deliver credible transition plans.

2. Anthesis Group

Anthesis bills itself as the world’s largest pure‑play sustainability advisory and solutions firm, with over 1,400 experts across decarbonization, ESG, circular economy, and digital. Backed by private equity, it has grown rapidly through acquisitions of niche sustainability specialists.

Key features:

• Full suite of services including science‑based targets, net‑zero strategy, ESG strategy and reporting, sustainable product design, and digital transformation for sustainability.
• “Activator” programs that translate strategy into operational change across value chains.
• Strong sector programs in FMCG, retail, technology, and industrials.

Industries served:

• Mid‑to‑large corporates across consumer, retail, manufacturing, technology, and services.

Pros:

• Pure‑play sustainability focus with multi‑disciplinary teams and global coverage.
• Agile and innovation‑oriented, with strong experience operationalizing sustainability and ESG.

Cons:

• Rapid growth and many acquisitions may mean integration maturity varies by region.
• Less brand recognition among some board‑level stakeholders compared with century‑old strategy firms.

Best for: Companies looking for a dedicated sustainability partner to move from strategy to execution across decarbonization, circularity, and ESG.

3. McKinsey & Company (McKinsey Sustainability)

McKinsey Sustainability is a dedicated platform within McKinsey & Company aimed at helping clients decarbonize, build green businesses, and navigate ESG and energy transition. The firm combines top‑tier strategy, analytics, and transformation support with deep climate and sector expertise.

Key features:

• Net‑zero and decarbonization strategies across sectors, including brown‑to‑green transition, asset retirement, and new green business building.
• Climate‑ and energy‑transition scenarios, sector roadmaps, and macro‑transition perspectives.
• Large‑scale transformation programs aligned to SBTi and net‑zero commitments.

Industries served:

• Global corporates, governments, investors, and development institutions.

Pros:

• Strong CEO/board‑level access, sector strategy depth, and change‑management capabilities.
• Extensive thought leadership on climate, transition finance, and sector pathways.

Cons:

• Premium pricing and project scale can be prohibitive for smaller organizations.
• Often requires pairing with specialist implementers for detailed technical work.

Best for: Large organizations seeking top‑tier strategy support on net‑zero and energy transition, often as part of broader corporate transformation.

4. Deloitte Sustainability & Climate

Deloitte has invested at least $1 billion to expand its global Sustainability & Climate practice, positioning it as one of the largest integrated ESG consulting platforms. The practice spans advisory, assurance, tax, and technology services.

Key features:

• Support for clients to embed sustainability into strategy, operations, tax, and reporting, including CSRD/ISSB and other regulations.
• Deloitte Center for Sustainable Progress, providing research, data‑driven analysis, and sustainability thought leadership.
• Cross‑functional capabilities across decarbonization, nature, sustainable finance, and supply‑chain transformation.

Industries served:

• Corporates and financial institutions across sectors worldwide.

Pros:

• Unmatched scale and breadth across consulting, audit, and tax.
• Strong ability to link ESG with finance, risk, and compliance.

Cons:

• As a multi‑service network, experience can vary across countries and sector teams.
• Some clients may perceive conflicts when the same firm provides assurance and advisory.

Best for: Large enterprises needing end‑to‑end ESG and climate support—from strategy to reporting, systems, and assurance—at global scale.

5. EY Sustainability

EY provides sustainability and ESG services across strategy, implementation, reporting, and assurance, with strong presence in markets like India and Europe. It emphasizes “value‑led sustainability” that creates long‑term stakeholder and shareholder value.

Key features:

• ESG strategy and transformation, including materiality, governance, and operating‑model design.
• Climate and decarbonization services addressing physical and transition risks, market shifts, and regulations.
• ESG reporting and assurance, including CSRD, BRSR, and other jurisdictional frameworks, often supported by proprietary tools such as EY ESG Compass.

Industries served:

• Corporates and financial institutions across sectors, including strong coverage in emerging markets.

Pros:

• Deep reporting and assurance experience, useful for companies facing new mandatory disclosures.
• Strong regional teams (e.g., EY India) with local regulatory expertise.

Cons:

• As with other Big Four firms, independence rules may limit advisory for audit clients.
• More focused on corporate and financial sectors than on early‑stage ventures.

Best for: Firms needing integrated ESG strategy, reporting, and assurance, especially where regulatory alignment and investor‑grade disclosures are central.

6. PwC Sustainability

PwC’s global sustainability practice has been recognized as a global leader in ESG and sustainability consulting, with more than 10,000 sustainability practitioners and broad tech alliances. It offers services from ESG strategy and reporting to sustainable finance and nature‑positive solutions.

Key features:

• ESG strategy, materiality, and transformation programs across sectors.
• Sustainable finance and ESG financial advisory, including ESG due diligence, valuation, and sustainability‑linked financing.
• Nature‑positive and climate‑resilience solutions, including climate‑change consulting and community‑focused programs.

Industries served:

• Large corporates, governments, and financial sector clients globally.

Pros:

• Strong integration of ESG with deals, corporate finance, and valuation.
• Recognized leadership in Verdantix Green Quadrant for ESG and sustainability consulting.

Cons:

• Similar independence and multi‑service complexity issues as other Big Four.
• May be less attractive for very small companies due to fee levels and engagement models.

Best for: Enterprises seeking a global partner for ESG strategy, reporting, and sustainable finance, particularly where transactions and capital markets are central.

7. KPMG Sustainability & Climate

KPMG’s sustainability and climate practice helps clients with ESG strategy, reporting, decarbonization, and risk, backed by its own ambitious climate commitments. Verdantix research highlights KPMG among leaders in climate‑change consulting.

Key features:

• Corporate sustainability and climate‑strategy services integrating climate risks into operating models.
• Support for ESG reporting, climate resilience, and low‑carbon investment decisions.
• Strong assurance and risk‑management heritage.

Industries served:

• Corporates and public‑sector entities across industries.

Pros:

• Strong risk and assurance orientation useful for regulated sectors.
• Clear internal climate targets and sustainability commitments, supporting credibility.

Cons:

• Similar constraints as other Big Four in terms of independence and project selection.
• Sustainability may be one of many service lines for some local practices.

Best for: Organizations with strong risk, regulation, and assurance requirements, needing climate and ESG embedded into governance and reporting.

8. WSP

WSP is a global engineering and professional‑services firm that has become a leading environmental and sustainability consultancy, with around 8.4% global market share in environmental and sustainability consulting revenues according to Environment Analyst. It combines climate, resilience, and sustainability strategy with deep technical delivery in infrastructure and the built environment.

Key features:

• Climate, resilience, and sustainability services at enterprise, asset, and project levels.
• Strong capabilities in climate‑risk assessment, adaptation planning, and nature‑positive design.
• Integration of ESG into major infrastructure, transport, water, and energy projects.

Industries served:

• Infrastructure owners, cities, transport, water, energy, and industrial clients.

Pros:

• Recognized as the world’s leading environmental and sustainability consulting firm by revenue share.
• Strong on‑the‑ground delivery capability for complex infrastructure and adaptation projects.

Cons:

• More engineering‑centric than some pure‑strategy sustainability firms.
• Best fit for capital‑projects and asset‑heavy sectors rather than pure services firms.

Best for: Governments, cities, and asset‑intensive companies needing climate‑resilient infrastructure, adaptation strategies, and sustainability embedded in capital projects.

9. AECOM

AECOM is a Fortune 500 infrastructure consulting firm providing advisory, planning, design, engineering, and program management for transport, buildings, water, and new energy. Through its “Sustainable Legacies” strategy it has embedded ESG and sustainability into both its own operations and client offerings.

Key features:

• Advisory and technical services across the project lifecycle with ESG and sustainability integrated into design and delivery.
• Sustainable Legacies framework focused on building social equity, driving positive environmental change, achieving net zero, and making strategic ESG actionable.
• Strong capabilities in nature‑based solutions across the built environment and land‑use projects.

Industries served:

• Public and private‑sector clients in transport, buildings, water, energy, and environment.

Pros:

• Trusted infrastructure partner with strong ESG and resilience lens.
• Ability to implement sustainability in physical assets at scale.

Cons:

• Less focused on corporate‑level ESG strategy compared to management‑consulting and Big Four firms.
• Most relevant where infrastructure and engineering are core.

Best for: Clients looking to embed sustainability and resilience into major infrastructure, urban development, and environmental projects.

10. South Pole (Climate Consulting)

South Pole is a Swiss‑based climate solutions provider known for its climate‑consulting and carbon‑market expertise. Alongside project development and carbon credits, its consulting arm helps organizations measure emissions, manage climate risk, and design net‑zero strategies.

Key features:

• Climate risk management, carbon footprinting, and science‑based target setting.
• Climate‑strategy and net‑zero roadmaps for corporates and financial institutions.
• Integration of consulting with access to high‑integrity climate projects and voluntary carbon markets.

Industries served:

• Corporates across sectors, financial institutions, and public entities.

Pros:

• Strong blend of strategic climate advisory and market‑side expertise in carbon projects.
• Global presence with experience in emerging markets.

Cons:

• Heaviest concentration in climate and carbon; broader ESG topics may require additional partners.
• Public scrutiny of carbon markets means buyers must stay closely aligned with evolving integrity standards.

Best for: Organizations seeking a partner focused on climate strategy, carbon markets, and net‑zero implementation, especially when credits and project finance are part of the plan.

11. Accenture

Accenture brings sustainability consulting at enterprise scale, especially where climate, operations, technology, and data intersect. It is a strong fit for organizations embedding ESG into core systems, supply chains, and decarbonization programs.

Key features:

• Net Zero Transitions support focused on moving from targets to tangible decarbonization outcomes.
• Value-chain sustainability services designed to embed sustainability into supply chains and operations.
• Sustainability measurement and technology capabilities covering ESG data, financial measurement, and digital integration across enterprise systems.

Industries served:

• Corporates across sectors, financial institutions, and public entities.

Pros:

• Strong technology, data, and systems-integration capability.
• Recognized leader in net-zero consulting and IT sustainability services.

Cons:

• Best suited to large-scale transformations and enterprise budgets.
• Can be more implementation-heavy than organizations need for narrow advisory-only mandates.

Best for: Large enterprises that want a technology-led sustainability partner to embed climate and ESG into operations, value chains, and core systems.

12. Boston Consulting Group (BCG)

BCG combines board-level climate strategy with increasingly productized sustainability tools and supplier programs. It is especially strong for carbon-intensive sectors and organizations needing rigorous transition strategy backed by analytics.

Key features:

• Climate and sustainability strategy supported by sector roadmaps and transition insights.
• CO2 AI for footprint measurement, simulation, reduction, and tracking at scale.
• Supply Chain Net Zero Academy to upskill suppliers and procurement teams on Scope 3 decarbonization.

Industries served:

• Energy, industrials, consumer sectors, procurement-heavy companies, and financial institutions.

Pros:

• Strong strategy pedigree with practical sustainability tools.
• Good fit for Scope 3, circularity, and transition-finance topics.

Cons:

• Premium strategy-consulting model may require additional partners for deep implementation. 
• Often best suited to larger organizations with complex transformation agendas.

Best for: Large enterprises needing data-driven climate strategy, Scope 3 decarbonization, and circular-economy transformation.

13. Bain & Company

Bain links sustainability directly to value creation, with especially strong relevance in private equity, investor-led transformations, and decarbonization programs. It is a good fit where sustainability needs to show measurable commercial outcomes.

Key features:

• Sustainability consulting across energy transition, circular economy, sustainable finance, and decarbonization.
• ESG due diligence and portfolio value-creation support for private equity.
• Roadmaps covering carbon abatement, ESG strategy, and mobilization across portfolio companies and investment processes.

Industries served:

• Private equity firms, institutional investors, and large corporates across sectors.

Pros:

• Strong value-creation and investor lens.
• Deep private-equity ESG and due-diligence capability.

Cons:

• Best fit is often investor-led or large-scale strategic programs.
• May be less suitable for organizations seeking highly technical environmental engineering support.

Best for: Private-equity-backed businesses and large enterprises seeking to connect sustainability strategy with commercial value creation.

14. Systemiq

Systemiq is a systems-change company and certified B Corp that works across energy, nature and food, materials and circularity, urban areas, and finance. It is especially relevant for organizations seeking long-term transformation rather than narrow compliance advice.

Key features:

• Advisory and coalition-building across circular economy, sustainable finance, food systems, and clean energy.
• Combines strategic advisory with market design, policy engagement, and high-impact on-the-ground work.
• Strong positioning in plastics, food systems, finance, and broader systems transformation.

Industries served:

• Businesses, investors, policymakers, and cross-sector coalitions.

Pros:

• Distinctive systems-change lens and strong circular-economy expertise.
• Well suited to cross-value-chain and ecosystem-level transformation work.

Cons:

• Less ideal for buyers seeking only narrow reporting compliance or assurance.
• Systems-led model may be less suited to quick, tactical engagements.

Best for: Organizations pursuing circularity, food systems, sustainable finance, or broader system-level sustainability transformation.

15. Roland Berger

Roland Berger is a global strategy consultancy with strong European credentials in sustainability and climate action. It stands out in energy transition, hydrogen, industrial decarbonization, and EU-regulatory navigation.

Key features:

• Sustainability and climate-action consulting delivered through cross-disciplinary teams and a global network.
• Strong work in hydrogen, energy transition, industrial decarbonization, and strategic planning for clean technologies.
• Good fit for EU Taxonomy, CSRD readiness, and broader European transition topics.

Industries served:

• Energy, infrastructure, industrials, automotive, chemicals, and investors, particularly in Europe.

Pros:

• Strong European regulatory and industrial-transition expertise.
• Good fit for hydrogen and heavy-industry decarbonization.

Cons:

• European positioning may be more relevant than global generalists for some clients.
• Often stronger on strategy than on hands-on multi-service implementation.

Best for: European industrial and energy players navigating transition strategy, hydrogen, and EU sustainability regulation.

16. Oliver Wyman

Oliver Wyman’s Climate and Sustainability platform is particularly strong where climate strategy intersects with risk, finance, and regulatory pressure. It is especially well suited to financial institutions, insurers, and other regulated sectors requiring rigorous modelling and decision-useful analytics.

Key features:

• Climate-risk assessment models and climate-reporting support for regulated institutions.
• Climate Credit Analytics developed with S&P Global to assess counterparty risk from the low-carbon transition.
• Transition strategy, climate target setting, resilience, and financing-related advisory.

Industries served:

• Banks, insurers, financial institutions, and other regulated sectors.

Pros:

• Strong climate-risk and financial-analytics pedigree.
• Useful for institutions where sustainability must integrate with pricing, capital, and risk frameworks.

Cons:

• More risk- and finance-oriented than broad corporate ESG transformation firms.
• May not be the first choice for companies seeking mainly engineering or operational decarbonization support.

Best for: Financial institutions and regulated industries needing climate-risk modelling, transition analytics, and sustainability strategy tied to risk management.

Explore OneStop ESG Marketplace: ESG Software

How to choose the right sustainability consulting firm

1. Define primary drivers and scope

Organizations should first clarify whether the priority is regulatory compliance and reporting, deep decarbonization, supply‑chain transformation, nature and biodiversity, infrastructure resilience, or some combination of these. Strategy‑led firms like McKinsey and the Big Four excel at board‑level roadmaps and multi‑function transformations, while pure‑plays and engineering firms may be better for technical execution.

2. Match firm type to sector and asset base

Asset‑heavy industries may benefit most from ERM, WSP, AECOM, or Anthesis, which combine technical environmental skills with strategy. Service‑ and finance‑heavy sectors may lean toward McKinsey, Deloitte, EY, PwC, or KPMG, which integrate ESG with corporate finance, risk, and reporting.

3. Consider geographic presence and local regulatory expertise

Local rules such as CSRD in the EU, BRSR in India, and sectoral regulations require on‑the‑ground expertise. Global networks like the Big Four, McKinsey, and WSP offer broad footprints, while pure‑plays such as Anthesis and South Pole often have strong regional hubs.

4. Evaluate implementation depth versus high‑level strategy

Some firms specialize in high‑level strategy and operating‑model design, while others excel at implementation—engineering projects, systems rollout, data and analytics, and operational change. Buyers should check:

• Who will implement decarbonization levers, data systems, and reporting workflows?
• Is the same firm capable, or will integrators and specialist vendors be needed?

5. Assess cultural and collaboration fit

Sustainability transformations are multi‑year journeys that require strong cultural fit and co‑creation. Firms differ in style—from strategy‑heavy teams to technical engineers to pure‑play sustainability activists—and clients should select partners whose working styles and values align with internal teams.

Which sustainability consulting firm is right for your needs?

Business‑type alignment table

Conclusion

Sustainability consulting firms now play a central role in helping businesses respond to climate risk, regulatory pressure, investor scrutiny, and broader operational change. The firms profiled here reflect the full range of the market, from pure-play sustainability specialists and engineering-led consultancies to Big Four networks and strategy firms, each bringing different strengths across ESG reporting, decarbonization, sustainable finance, circularity, risk, and implementation.

The right partner depends on the nature of the challenge. Some organizations need technical depth in infrastructure, nature, and industrial transition, while others need board-level strategy, assurance readiness, enterprise systems integration, or climate-risk modelling. Sustainability, finance, and operations leaders can use this segmentation to build a shortlist aligned with their sector, regulatory exposure, and transformation goals, then assess firms based on execution capability, regional presence, and fit with long-term business priorities.

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