Background: Citizens with HIV and substance use problems returning from prison or jail experience numerous serious health outcomes, which is unsurprising given the challenges faced. Interventions are needed to relieve stress as a pathway to reduced substance use and improved health outcomes. Yoga is one intervention associated with stress-reduction, but there is limited research regarding yoga’s effect on substance use. Additionally, yoga in the U.S. is marketed towards White women so that people of color are sometimes excluded from practice. To fill these gaps, this randomized controlled trial explored yoga’s effect on the well-being of returning citizens with HIV and substance use problems, an underrepresented group in U.S. yoga studios. Methods: Thirty-two people were randomized to treatment as usual (TAU) and 32 people were randomized to a 12-week hatha yoga intervention. The yoga and TAU groups were compared on 1.) stress, antiretroviral therapy (ART) adherence, blood pressure and pulse at three-months post-baseline, controlling for the respective baseline dependent measure using analysis of covariance, and 2.) percentage of days of drug use at one, two and three-months post-baseline controlling for baseline drug use using generalized estimating equations. Qualitative interviews completed at three-months post-baseline explored yoga participants’ perceptions of the intervention. Transcripts were analyzed using thematic analysis. Results: Treatment condition comparison on mean stress reduction was significant [F (1,59)=9.24, p<.05], with yoga participants experiencing greater stress-reduction. Treatment condition comparison on percentage of days of substance use was significant [X2 (1)=11.47, p<.001], with yoga participants using substances on 20 % of the days and TAU using substances on 41 % of the days between baseline and program completion. There was no statistically significant effect on pulse, blood pressure or ART adherence. Qualitative interviews highlighted that yoga participants experienced social support, health improvements, and a feeling of well-being that complemented substance use recovery. Conclusion: Yoga can support well-being outcomes, including reduced stress and substance use among returning citizens with HIV and substance use problems.