Abstract Background Support groups for people living with HIV (PLWH) may improve HIV care adherence and outcomes. We assessed the impact of support group attendance on antiretroviral therapy (ART) adherence and viral suppression in four African countries. Methods The ongoing African Cohort Study (AFRICOS) enrolls participants at 12 clinics in Kenya, Uganda, Tanzania, and Nigeria. Self-reported attendance of any support group meetings, self-reported ART adherence, and HIV RNA are assessed every 6 months. Logistic regression models with generalized estimating equations were used to estimate adjusted odds ratios (aORs) and 95% confidence intervals (95% CIs) for support group attendance and other factors potentially associated with ART adherence and viral suppression. Results From January 2013 to December 1, 2019, 1959 ART-experienced PLWH were enrolled and 320 (16.3%) reported any support group attendance prior to enrollment. Complete ART adherence, with no missed doses in the last 30 days, was reported by 87.8% while 92.4% had viral suppression <1000copies/mL across all available visits. There was no association between support group attendance and ART adherence in unadjusted (OR 1.01, 95% CI 0.99–1.03) or adjusted analyses (aOR 1.00, 95% CI 0.98–1.02). Compared to PLWH who did not report support group attendance, those who did had similar odds of viral suppression in unadjusted (OR 0.99, 95% CI 0.978–1.01) and adjusted analyses (aOR 0.99, 95% CI 0.97–1.01). Conclusion Support group attendance was not associated with significantly improved ART adherence or viral suppression, although low support group uptake may have limited our ability to detect a statistically significant impact.