Coming out of the closet refers to the self-disclosure of one's sexual orientation to other people. A majority of gay men in mainland China are hesitant about coming out. Considerable research in Western contexts has demonstrated that coming out can alleviate gay men's psychological distress. The current study thus aims to understand the psychological impacts of coming out for gay men in mainland China. We employed a serial mediation model to examine the relationship between overall outness and psychological distress, with internalized homonegativity as the first-order mediator and perceived discrimination based on samesex sexual orientation (hereafter "perceived discrimination") as the second-order mediator. An online sample of 251 Chinese adult gay men (M age = 25.25 years, SD = 5.28 years) completed self-report measures of outness, internalized homonegativity, perceived discrimination, and psychological distress. Results showed that the negative association between overall outness and psychological distress was partially mediated by internalized homonegativity (indirect effect = À0.057, bias-corrected 95% confidence interval [À0.153, À0.011]), and serially mediated by internalized homonegativity and then perceived discrimination (indirect effect = À0.019, bias-corrected 95% confidence interval [À0.048, À0.007]), controlling for age. Additionally, we did not find the simple mediating effect of perceived discrimination between overall outness and psychological distress, which may be because coming out reduced oversensitivity and perception bias but increased the probability of actual discriminatory experiences. These results contribute to our understanding of how coming out affects psychological distress among Chinese gay men. Furthermore, this study may illuminate the design of psychological crisis intervention focusing on this group in mainland China.