This study examined the impact of stigma-related discussions on HIV and sexuality stigma among young Black men who have sex with men (YBMSM) using the HealthMpowerment.org (HMP) intervention. The analysis of 1,497 forum posts revealed that engaging in discussions about experienced HIV stigma was linked to a reduction in perceived HIV stigma, while discussions about anticipated stigma led to an increase in perceived stigma. Additionally, challenging sexuality-related stigma was associated with lower internalized homophobia, but discussing experienced stigma was linked to increased internalized homophobia and sexual prejudice over time. The findings highlight the potential of online forums in stigma reduction and suggest that interventions incorporating such forums could enhance HIV prevention and care efforts.