Cigarette smoking, as a significant public health problem worldwide, deserves more attention. This research intended to assess the prevalence rate of smoking among college students self-identified as lesbian or gay, examine whether depression mediated the association between social support and smoking, and explore whether disclosure moderated the indirect effect of the mediation model. All data were collected by online questionnaires, yielding a total of 1,109 homosexual college students involved in the analysis. A moderated mediation analysis was adopted to uncover the connection between social support, depression, and cigarette smoking, with disclosure as the moderator. The prevalence of smoking was 7.4%, and lesbian females (12.5%) were more likely to report smoking than gay males (5.2%). Depression fully mediated the effects of social support on cigarette smoking (coefficient ab = -0.0097, 95% Boot CI: -0.0174 to -0.0029), accounting for 97.0% of the total effect. Further moderated mediation analyses revealed the indirect effect of depression was statistically significant in both disclosed (effect = 0.0737, 95% Boot CI: 0.0005 to 0.1502) and non-disclosed groups (effect = -0.0109, 95% Boot CI: -0.0183 to -0.0039). The prevalence of smoking among homosexual college students in China should not be neglected, especially among lesbian students. Interventions, such as encouraging greater disclosure and expanding social support, may help break the link between depression and smoking.