Physical activity (PA) interventions have shown promising in improving core symptoms of children and adolescents with ADHD, yet treatment dropout may pose a challenge to routine implementation in clinical practice. We conducted a meta-analysis to investigate the prevalence and predictors of treatment dropout from PA interventions in children and adolescents with ADHD. Electronic databases were searched from inception until 06/2016. Randomized control trials of PA interventions in children and adolescents with ADHD reporting dropout rates were included. A random effects meta-analysis and meta-regression analyses were performed. In 8 studies involving 9 PA intervention arms, 148 children or adolescents assigned to a PA intervention (mean age range = 8.2–15.8 years, 87.8% male) were included. The trim and fill adjusted treatment dropout rate was 17.5% (95%CI = 9.8%–29.4%). The prevalence of dropouts in exercisers was not significantly different from the dropouts in control conditions (odds ratio, OR = 1.12; 95%CI = 0.48–2.65; I2 = 0). Lower dropout was observed in sports interventions compared with structured aerobic exercise or yoga (p = 0.049). A higher proportion of male participants (β = 0.05; 95%CI = 0.001 to 0.10; p = 0.045, R2 = 1.0) appeared to moderate higher dropout rates from PA interventions. Our findings suggest that in order to maximize PA participation, and therefore health benefits, sports-related interventions should be offered in the multidisciplinary treatment of children and adolescents with ADHD. Our data also suggest that males with ADHD may be more likely to dropout. Dropout rates are comparable to control conditions, suggesting that PA interventions are feasible in adolescents with ADHD.