This study explores the relationship between five types of board diversity and environmental innovation (EI), with a focus on the moderating role of new quality productivity (NQP). Using an entire sample from China's A-share market (2013–2022), the study examines how board compositions—specifically top managers, independent directors, female directors, supervisory directors, and blockholder directors—influence EI performance. The entropy method is adopted to measure NQP, while robustness and endogeneity checks, alongside two-step system GMM estimation, reinforce the credibility of the findings. Our findings suggest that while board diversity generally benefits EI, only certain types, such as top managers and female directors, positively impact EI. In contrast, diversity among supervisory and blockholder directors has negative effects, and independent directors show no significant influence. NQP can amplify these effects, although its impact varies by board member type. This study emphasizes that aligning board diversity with environmental objectives is essential, not just merely increasing diversity. Instead, specific board compositions and roles determine whether diversity effectively drives EI, answering that “more is not always better” regarding diversity's role in environmental goals. Future research could examine additional mechanism and explore NQP's impact on sustainability across various contexts.