Proactivity is vital to innovative changes in the workplace. However, existing research on proactivity has rarely addressed how human resources management (HRM) systems induce proactive behavior and influence group innovation. Indeed, HRM systems are considered primary tools that organizations utilize to derive specific behaviors from their employees. Thus, examining the relationship between HRM systems and proactivity and its link to subsequent outcomes is a worthwhile pursuit. To examine how HRM systems influence proactive behavior, we investigated the effects of HRM systems on three psychological states, namely, role breadth self-efficacy, felt responsibility for change, and trust in management. Furthermore, we suggested that, facilitated by members’ proactive behaviors, group creative processes can spur group innovation. We conducted two multilevel studies to test our hypotheses, and the results generally supported our theoretical arguments. Exploring the process through which HRM influences proactive behavior and subsequent innovation outcomes, this study contributes to the literatures on HRM, proactivity, and innovation by elucidating the HRM–innovation relationship and suggesting HRM systems as meaningful antecedents to proactivity.