Interest in sport as a tool for behavioral HIV prevention has grown substantially in the past decade. With dozens of organisations now using sport-based HIV prevention (SBHP) approaches and upcoming randomized controlled trials in South Africa and Zimbabwe, there is a pressing need to synthesize previous evaluation findings and identify gaps in existing research. A systematic review on the effectiveness of SBHP interventions was carried out, identifying both published and unpublished studies on SBHP interventions that measured effectiveness quantitatively. Study quality was scored using an adapted Newcastle-Ottawa Scale. Random-effects meta-analyses were carried out across studies for effects on six categories of HIV-related outcomes. The review identified 952 publications, 21 of which met inclusion criteria. No randomised controlled trials on SBHP interventions and no studies assessing biological outcomes were identified. Mean study quality score was 5.1 (SD 3.1) out of 20 points. Overall strong evidence was observed for positive effects on HIV-related knowledge (RR = 1.26, 95 % CI = 1.15-1.37), stigma (RR = 1.13, 95 % CI = 1.02-1.24), self-efficacy (RR = 1.22, 95 % CI = 1.02-1.41), reported communication (RR = 1.24, 95 % CI = 1.06-1.41), and reported recent condom use (RR = 1.29, 95 % CI = 1.00-1.59). Generally, the review found encouraging evidence for some short-term effects but relied predominantly on low-quality studies. More rigorous research on SBHP is needed to objectively assess effectiveness. Randomised controlled trials could play an important role in guiding policies, strategies, and funding related to SBHP.