© 2021 Informa UK Limited, trading as Taylor & Francis Group.Narrative reviews indicate psychological and social benefits of sport participation for the ageing population. However, no quantitative synthesis of quantitative studies on this topic has been conducted yet. We evaluated the magnitude and heterogeneity of the effects of sport participation on psychosocial outcomes for middle-aged and older adults (>35 years). Ten databases were searched in July 2020. Quantitative studies (k = 25) of middle-aged and older adults, measuring at least one psychosocial outcome of sport participation were included. Multilevel meta-analysis showed that the association between sport participation and psychosocial outcomes was small, yet significant. Moderation analyses revealed that the pooled effect differed according to outcome type; small to moderate associations were observed for social, positive psychological, perceived physical, and cognitive outcomes, but not for negative psychological outcomes. Risk of bias, assessed using the QualSyst tool, indicated low quality of evidence. Our findings suggest that sport participation is associated with multiple psychosocial benefits for middle-aged and older adults that appear invariant across participant-related and sport-related characteristics. We found no evidence of publication bias, but studies were underpowered and rated as low quality. Our review provides quantitative evidence for the psychosocial benefits of sport participation for adults, complementing existing qualitative research on this topic.