Background: The school environment is globally recognised as a key setting to promote child and adolescent physical activity. School recess contributes up to 40% of the school day and recommended physical activity levels, providing a critical physical activity promotion opportunity for children and adolescents. Objective: To examine the effectiveness of school recess interventions on children’s and adolescents’ physical activity (PA) and sedentary behaviour (SED) during this time. Design: Systematic review and meta-analysis. Data Sources: EBSCOhost (Academic Search Complete, Education Source, ERIC, Global Health, MEDLINE complete, SPORTDiscus), Scopus, and ProQuest electronic databases with full text. Results: Forty-three studies were included in the systematic review, trialling eight different intervention strategies including loose equipment, structured recess, and multicomponent studies. The meta-analysis included 16 studies. Overall, between group mean difference for: (i) time spent in moderate to vigorous-intensity physical activity (MVPA) for randomised controlled trials (RCTs) (n = 6) was 0.18 (95% CI − 0.00 to 0.36) with a marginal significant effect of Z = 1.93 (p = 0.05), (ii) time spent in MVPA for non-RCTs (n = 7) was 0.52 (95% CI − 0.01 to 1.03) with an overall effect of Z = 1.99 (p = 0.05), (iii) time spent in sedentary behaviour for RCTs (n = 3) was − 0.48 (95% CI − 1.38 to 0.43) with an overall effect of Z = 1.03 (p = 0.30). All outcomes had high heterogeneity. Conclusion: School recess interventions show promise for increasing MVPA. It was difficult to draw strong conclusions due to low study numbers in the meta-analysis and varied intervention designs. Interventions may need to focus on single component strategies (e.g., loose equipment) to improve understanding of outcome effects for future studies.