<p>Evidence supports the efficacy of positive psychology interventions (PPIs) for enhancing mental well-being, yet the effectiveness of brief, multicomponent PPIs and the role of civic engagement within educational settings remain inadequately understood. This study investigated both the impact of an 8-week positive education programme on student mental well-being in Hong Kong and other Asia Pacific regions, and examined civic engagement’s mediating role in intervention outcomes. Participants (<i>N</i> = 112) were randomly assigned to experimental or waitlist control groups. The intervention incorporated multiple positive psychology topics and civic engagement components. The experimental group demonstrated significant improvements in growth mindset, resilience, prosocialness, positive emotions, general health, and reduced insomnia severity compared to the waitlist control group, with civic engagement behaviors also showing a significant increase. Mediation analyses revealed that civic engagement mediated the relationship between resilience and well-being in the experimental group, while showing an unexpected negative association in the waitlist control group. This differential effect highlights civic engagement’s complex role in well-being interventions, while demonstrating the effectiveness of structured brief, multicomponent PPIs in enhancing participants’ well-being. The study reveals that structured support is potentially crucial for maximizing benefits. These insights inform the design of effective well-being interventions in higher education settings.</p>