BACKGROUND: Interventions to improve HIV service uptake are increasingly addressing inequitable and restrictive gender norms. Yet comparatively little is known about which gender norms are most salient for HIV testing and treatment and how changing these specific norms translates into HIV service uptake. To explore these questions, we implemented a qualitative study during a community mobilization trial targeting social barriers to HIV service uptake in South Africa. METHODS: We conducted 55 in-depth interviews in 2018, during the final months of a three-year intervention in rural Mpumalanga province. Participants included 25 intervention community members (48% women) and 30 intervention staff/community-opinion-leaders (70% women). Data were analyzed using an inductive-deductive approach. RESULTS: We identified three avenues for gender norms change which, when coupled with other strategies, were described to support HIV service uptake: (1) Challenging norms around male toughness/avoidance of help-seeking, combined with information on the health and preventive benefits of early antiretroviral therapy (ART), eased men's fears of a positive diagnosis and facilitated HIV service uptake. (2) Challenging norms about men's expected control over women, combined with communication and conflict resolution skill-building, encouraged couple support around HIV service uptake. (3) Challenging norms around women being solely responsible for the family's health, combined with information about sero-discordance and why both members of the couple should be tested, encouraged men to test for HIV rather than relying on their partner's results. Facility-level barriers such as long wait times continued to prevent some men from accessing care. CONCLUSIONS: Despite continued facility-level barriers, we found that promoting critical reflection around several specific gender norms, coupled with information (e.g., benefits of ART) and skill-building (e.g., communication), were perceived to support men's and women's engagement in HIV services. There is a need to identify and tailor programming around specific gender norms that hinder HIV service uptake.