Background <p>Juvenile idiopathic arthritis (JIA) frequently leads to reduced physical ability, diminished aerobic capacity, and impaired quality of life in children. Exercise has emerged as a promising adjunctive therapy; however its overall efficacy remains uncertain.</p> Objective <p>To assess the effects of exercise interventions on physical function, cardiorespiratory fitness, and health-related quality of life (HRQoL) in patients with JIA.</p> Methods <p>A systematic search of MEDLINE, Embase, and the Cochrane Library was conducted through 1, October 2025 to identify randomized controlled trials (RCTs) evaluating exercise in JIA. Eligible studies reported outcomes for at least one of the target domains. Meta-analyses were performed using fixed- or random-effects models, and risk of bias was assessed with the Cochrane risk of bias tool RoB2.</p> Results <p>Eight RCTs involving 405 participants met the inclusion criteria. Exercise interventions significantly improved functional measures, including child health assessment questionnaire (CHAQ) score (WMD = − 0.41; 95% CI: − 0.80 to − 0.03; <i>p</i> = 0.03) and 6-minute walk test (6MWT) distance (WMD = 26.70; 95% CI: 1.70 to 51.71; <i>p</i> = 0.04). Maximum heart rate (HRmax) also increased significantly (WMD = 7.27; 95% CI: 3.69 to 10.84; <i>p</i> &lt; 0.01), while changes in peak oxygen consumption (VO₂peak) and health-related quality of life (HRQoL) scores were not statistically significant.</p> Conclusion <p>Exercise interventions improve both subjective and objective measures of physical function in patients with JIA. Given the inconsistent effects on cardiorespiratory fitness and HRQoL, further high-quality RCTs are warranted to clarify long-term benefits and determine optimal implementation.</p> Trial registration <p>PROSPERO registration number: CRD420251048687</p>