Marsh & McLennan Companies, Inc. is a global professional services firm offering clients advice and solutions in risk, strategy, and people. With a presence in over 130 countries, the company operates through its four main businesses: Marsh, Guy Carpenter, Mercer, and Oliver Wyman. These subsidiaries provide a wide range of services including insurance broking, risk management, reinsurance, talent management, investment advisory, and management consulting.

The company is committed to integrating sustainability into its business operations and client services. Marsh & McLennan has been actively working on reducing its carbon footprint and enhancing its environmental, social, and governance (ESG) performance. The firm has set ambitious targets to achieve net-zero greenhouse gas emissions by 2050, aligning with the Paris Agreement's goals. It has also been recognized for its efforts in promoting diversity, equity, and inclusion within its workforce.

Marsh & McLennan publishes an annual ESG report that outlines its sustainability initiatives and progress. The report highlights the company's commitment to responsible business practices and its role in helping clients navigate the transition to a low-carbon economy. Additionally, the firm is a signatory to the United Nations Global Compact, reinforcing its dedication to sustainable and ethical business practices.

Despite these efforts, detailed information on specific sustainability certifications or accreditations for Marsh & McLennan is limited. However, the company's ongoing initiatives and public commitments indicate a strong focus on sustainability and corporate responsibility.