["Business Strategy and the Environment, Volume 35, Issue 3, Page 3878-3897, March 2026. ", "\nABSTRACT\nThis research examined whether board sustainability committees (SCs) influence the known connection between board gender diversity and environmental, social and governance (ESG) performance among companies in 10 different sectors listed in FTSE 350. Analysis of data spanning from 2010 to 2023 from the London Stock Exchange, Refinitiv and Fame databases assessed for moderation effect. Gender diversity was evaluated based on the proportion of women on boards (Blau and Shannon indices). Findings indicated board gender diversity's direct and positive impact on overall ESG performance and on each dimension of ESG performance; having a sustainability committee moderated this by amplifying the positive relationship between gender diversity and ESG performance. This research offers insights for managers, investors and regulators regarding the importance of gender diversity and sustainability committees in ESG performance, thereby facilitating more informed decision‐making around corporate governance regulation enhancing female representation on boards and subcommittees, thus safeguard stakeholders' interests.\n"]