Poverty fuels risky sexual behaviors associated with HIV infection among youth. Interventions like cash transfers may mitigate HIV risk. We explored the role of broader social protection (including food, educational, and social transfers) in reducing HIV risk among 15-24-year-olds in Southern Africa. We analyzed Population-based HIV Impact Assessment surveys data from 31,317 youth in eSwatini, Lesotho, Malawi, Namibia, Zambia, and Zimbabwe (2015-2017). Using inverse probability-weighted multivariable logistic regression, we examined associations between types of social protection and condomless sex, multiple partnerships, and high-risk sexual behaviors. Food support was associated with reduced odds of condomless sex (OR 0.71 [95% CI 0.61-0.82]), multiple partnerships (0.77 [0.63-0.95]), and high-risk sex (0.70 [0.60-0.82]). Educational support was associated with reduced odds of condomless sex (0.57 [0.46-0.59]) and high-risk sex (0.59 [0.47-0.73]). Social transfers were associated with reduced odds of condomless sex (0.62 [0.54-0.70]) and high-risk sex (0.50 [0.44-0.56]). The benefits of social protection varied across countries. Educational support was associated with reduced odds of any HIV risk factors in eSwatini, Zambia, and Zimbabwe. However, the protective effect of social transfers was only observed in eSwatini, and the benefit of food support was only significant in Namibia. Furthermore, protective associations were more pronounced among females than males. This study underscores the potential of social protection to strengthen HIV prevention efforts by mitigating poverty-related risk factors, particularly for adolescent girls and young women in Southern Africa. The impact of specific programs appears context-dependent, highlighting the need for tailored interventions.