Video games are identified as rich environments for the extension and development of the self. Gender swapping is common in massively multiplayer online role-playing games (MMORPGs). Drawing on self-discrepancy theory, this study aims to examine whether variables reflecting actual-ideal self-discrepancy in gender-atypical behaviors and gender identity contribute to gender swapping. Specifically, we examine associations between childhood gender nonconformity (CGN), adulthood gender nonconformity (AGN), gender dysphoria, and gender-swapping. An online survey was conducted with 586 players of MMORPGs in China. CGN, AGN, and gender dysphoria were positively associated with gender-swapping. Gender dysphoria fully mediated the associations between CGN and gender swapping. The current findings indicate the effects of gender-atypical behaviors and gender identity on gender swapping among Chinese MMORPGs players.