Gender-based power imbalances place women at significant risk for sexual violence, however, little research has examined this association among women living with HIV/AIDS. We performed a cross-sectional analysis of relationship power and sexual violence among HIV-positive women on anti-retroviral therapy in rural Uganda. Relationship power was measured using the Sexual Relationship Power Scale (SRPS), a validated measure consisting of two subscales: relationship control (RC) and decision-making dominance. We used multivariable logistic regression to test for associations between the SRPS and two dependent variables: recent forced sex and transactional sex. Higher relationship power (full SRPS) was associated with reduced odds of forced sex (AOR = 0.24; 95 % CI 0.07–0.80; p  = 0.020). The association between higher relationship power and transactional sex was strong and in the expected direction, but not statistically significant (AOR = 0.47; 95 % CI 0.18–1.22; p  = 0.119). Higher RC was associated with reduced odds of both forced sex (AOR = 0.18; 95 % CI 0.06–0.59; p  < 0.01) and transactional sex (AOR = 0.38; 95 % CI 0.15–0.99; p  = 0.048). Violence prevention interventions with HIV-positive women should consider approaches that increase women’s power in their relationships.