Under the goal of multi-stakeholder co-governance in the context of China’s modern enterprise system with distinctive characteristics, this study systematically examines the impact mechanism of core management stability on corporate social responsibility (CSR) fulfillment, using restrictive provisions in corporate bylaws as the research entry point. By constructing a theoretical framework that incorporates the dual effects of “implicit incentive effect” and “self-interest effect” of management, this paper conducts empirical tests using data from listed companies on the Shanghai and Shenzhen main boards from 2007 to 2020. The findings reveal that in China’s market environment, restrictive provisions primarily exhibit a self-interest effect, significantly inhibiting CSR fulfillment. While improved corporate governance can mitigate this negative impact, explicit incentive mechanisms tend to reinforce the inhibitory effect. Further mechanism analysis indicates that restrictive provisions enhance management stability, which in turn (1) strengthens informal relationships centered around management, forming self-interested capital, and (2) diverts resources toward domains more favorable to management, creating a crowding-out effect—both of which constitute key channels for suppressing CSR fulfillment. This study provides important theoretical insights and policy implications for improving corporate governance mechanisms and promoting CSR practices.