PURPOSE OF REVIEW: This review synthesizes evidence on the use of crowdsourcing to improve HIV/sexual health outcomes. RECENT FINDINGS: We identified 15 studies, including four completed randomized controlled trials (RCTs), one planned RCT, nine completed observational studies, and one planned observational study. Three of the four RCTs suggested that crowdsourcing is an effective, low-cost approach for improving HIV testing and condom use among key populations. Results from the observational studies revealed diverse applications of crowdsourcing to inform policy, research, and intervention development related to HIV/sexual health services. Crowdsourcing can be an effective tool for informing the design and implementation of HIV/sexual health interventions, spurring innovation in sexual health research, and increasing community engagement in sexual health campaigns. More research is needed to examine the feasibility, acceptability, and effectiveness of crowdsourcing interventions, particularly in low- and middle-income countries.