We conducted a pilot randomized controlled trial of Game Changers, a 6-session group intervention that empowers people with HIV to be HIV prevention advocates in their social networks. Ninety-nine people with HIV (51 intervention, 48 wait-list control) and 58 of their social network members (alters) completed baseline and 5- and 8-month post-baseline assessments. Results indicated high acceptability, demonstrated by participants’ and facilitators’ positive attitudes qualitatively and favorable ratings of intervention sessions quantitatively, and high feasibility (76% attended all intervention sessions). Intention-to-treat analyses indicated significantly increased HIV prevention advocacy among HIV-positive participants and alters [b (SE) = 0.4 (0.2), p =.017; b (SE) = 0.4 (0.2), p =.035]; reduced internalized HIV stigma [b (SE) = − 0.3 (0.1), p =.012], increased HIV-serostatus disclosure [b (SE) = 0.1 (0.1), p =.051], and increased social network density among HIV-positive participants [b (SE) = 0.1 (0.03), p =.004]; and marginally reduced condomless sex among alters [OR (95% CI) = 0.3 (0.1–1.2), p =.08]. Positioning people with HIV as central to prevention has the potential to reduce stigma and improve prevention outcomes throughout social networks.