Purpose Young nurses represent the primary workforce for the future of the nursing industry. However, they often experience a heightened sense of overqualification, which can easily lead to silence behavior, negatively impacting personal well-being, organizational development, and the quality of nursing care. The purpose of this study is to explore the relationship between perceived overqualification and silence behavior among young nurses, as well as the mediating role of surface acting and the moderating role of perceived organizational support. Method The Scale of Perceived Overqualification, the surface acting dimension of the Emotional Labor Scale, the Employee Silence Scale, and the Perceived Organizational Support Scale were used to conduct a cross-sectional survey of 1,095 young nurses from six general hospitals in China. A moderated mediation model was constructed, and data were analyzed using Hayes’ PROCESS macro (Models 4 and 59). Results There are significant correlations among perceived overqualification, surface acting, silence behavior, and perceived organizational support (p < 0.01). The direct effect of perceived overqualification on silence behavior was significant (Effect = 0.081, 95% CI = [0.024, 0.138]), and the mediating effect of surface acting on the relationship between perceived overqualification and silence behavior was also significant (Effect = 0.111, 95% CI = [0.084, 0.142]). Furthermore, perceived organizational support played a negative moderating role in the relationships among perceived overqualification, surface acting, and silence behavior. Specifically, when perceived organizational support was high, both the direct and indirect effects of perceived overqualification on silence behavior were weakened and even showed a tendency to reverse direction. Conclusion Reducing young nurses’ perceived overqualification, decreasing surface acting, and enhancing perceived organizational support may help reduce the occurrence of silence behavior. Nursing managers should provide young nurses with appropriate career development opportunities, offer training in emotional regulation and stress management, and foster an open, psychologically safe communication environment and supportive organizational climate. These strategies may effectively intervene in silence behavior and contribute to improving team vitality and the quality of nursing services.