This study investigated the effect of prosocial video game exposure on sharing behavior in Chinese preschoolers and tested the mediating role of empathy as well as the moderating roles of age and gender. A total of N = 120 children aged 4–6 years (50% girls, 50% boys; M_age = 5.0, SD = 0.82) from two Chinese kindergartens participated in this between-subjects design experiment. The results showed that the preschoolers who played prosocial video games exhibited more sharing behavior than those who played neutral video games. Empathy, especially affective empathy, was found to mediate the association between playing prosocial video games and sharing behavior. This suggests that empathy training programs, especially those that promote affective empathy, may be an effective means of promoting sharing behavior in children. The mediating effect was mainly observed for girls and older children. Girls and older children may therefore be the target group for sharing behavior education programs that aim to increase empathy in playing prosocial video games. Nevertheless, promoting sharing behavior in younger children and boys is equally important and deserves attention in future research.