In the past three years, many studies have been conducted on dockless bike sharing (DBS) around the world. However, these studies have focused minimally on the problem of damaged bicycles, which is critical to a DBS system’s operating efficiency, user satisfaction and platform sustainability. The objectives of this study are to develop an integrated theoretical framework based on the normative activation model and examining the impact mechanism of users’ willingness to participate in repairing damaged bicycles. To achieve these objectives, a questionnaire survey was undertaken with a total of 633 DBS users from 27 provinces and municipalities in Mainland China. Empirical results confirm that the theoretical framework can provide a strong rationale for the investigation into DBS users’ willingness to participate in repairing damaged bicycles. Furthermore, internal psychological factors (i.e., personal norms, awareness of consequences, and perceived consumer effectiveness) and external intervention factors (i.e., platform incentives and service response efficiency) had positive effects on users’ participation willingness. Nevertheless, information publicity did not play a significantly direct role but indirectly affected the participation willingness through personal norms. Service response efficiency tended to moderate the impacts of personal norms and awareness of consequences on participation willingness. Eventually, some practical approaches to motivating users to participate in repairing damaged bicycles are proposed. This study extends the theory of normative activation model to better understand the behaviors of DBS users who participate in repairing damaged bicycles, and contributes significant theoretical and practical insights to the sustainability of DBS systems.