<p>Transgender women in India experience a disproportionate HIV burden, but the pathways linking intersecting stigmas and condomless receptive anal sex (CAS) have not been elucidated. Using minority stress theory, and psychological mediation and intersectionality frameworks, we tested the mediating and synergistically interacting pathways linking these stigmas to HIV risk. Between November 2020 and March 2022, we conducted a prospective three-wave cohort study among 500 trans women in Mumbai and Chennai. We assessed stigmas (transgender identity, perceived HIV, sex work), five psychosocial variables (depression, anxiety, problematic alcohol use, internalized transprejudice, social support), and CAS with male nonregular partners. We used causal mediation analysis to examine indirect pathways between stigma and CAS. We also tested for synergistic effects. Baseline levels of all three stigmas were high. In Wave-2, we noted relatively high prevalence rates of anxiety (38%), internalized transprejudice (46%), low social support (46%), depression (15%), alcohol use (15%), and CAS (61%, Wave-2; 81%, Wave-3). In mediation analyses, we found that stigmas increased anxiety and depression while eroding protective social support, each of which subsequently increased CAS risk. Social support and anxiety showed the strongest and most consistent indirect effects across stigma types, whereas depression mediated associations primarily for transgender identity and HIV-related stigmas. We demonstrated strong synergistic interactions between specific stigma combinations and anxiety, depression, problematic alcohol use, and low social support. The findings underscore the need for multicomponent interventions that simultaneously address stigmas and their psychosocial consequences, including screening and treatment for depression and anxiety, while bolstering social support.</p>