Mobile payment platforms not only streamline users’ financial transactions but also encourage their participation in investment activities and additional services. To deliver personalized financial services, it is essential to collect users’ personal information. This study aims to investigate the factors influencing users’ willingness to engage in self-disclosure within mobile payment platforms, thereby assisting practitioners in efficiently allocating resources and maximizing returns on investments dedicated to promoting user self-disclosure. Consequently, this study focuses on examining how institutional mechanisms influence users’ self-disclosure behavior within these platforms. The authors developed a comprehensive framework that elucidates the influence of institutional mechanisms on users’ self-disclosure, mediated by trust and privacy concerns. To empirically validate our research model, we administered an online survey targeting Alipay users in China. Subsequently, we analyzed 559 valid survey responses utilizing partial least squares structural equation modeling (PLS-SEM). The results indicate that trust and privacy concerns jointly influence users’ self-disclosure behavior when utilizing mobile payment platforms. Moreover, key institutional mechanisms can effectively foster trust and alleviate privacy concerns, ultimately facilitating users’ willingness to self-disclose. Our research shifts scholarly focus from conventional adoption to users’ self-disclosure in the mobile payment field and enhances the existing self-disclosure research by identifying the impact of institutional mechanisms on users’ self-disclosure behavior.