ABSTRACT This systematic review examined the etiologic association between physical activity (PA) and indicators of childhood overweight/obesity (OV/OB) and metabolically unhealthy obesity (MUO) risk. Original peer‐reviewed English reports published between January 01, 2013, and June 30, 2024, were retrieved from MEDLINE and Scopus. A total of 106 prospective epidemiological studies and randomized controlled trials (RCTs) conducted in Western countries among 2‐ to 19‐year‐olds with ≥12‐month follow‐up were eligible. Study quality was evaluated through risk of bias (RoB). Regarding OV/OB, epidemiological studies ( n = 86, 57% high‐RoB) revealed a protective effect of certain accelerometry‐measured exposures: moderate‐to‐vigorous PA ( n = 17/32), vigorous PA ( n = 10/15), substituting lower‐intensity with higher‐intensity PA ( n = 7/11), and longitudinally sustaining high PA ( n = 3/3). Of the 16 RCTs (31% high‐RoB), 10 were successful and most utilized long‐term (≥ 1‐year) multicomponent PA interventions incorporating behavior change techniques. Random‐effects meta‐analysis of RCTs revealed a beneficial effect of PA on body mass index (BMI) ( n = 5: −0.42 [95% CI: −0.64, −0.21] kg/m 2 ) and BMI z ‐score ( n = 5: −0.09 [95% CI: −0.14, −0.04] SD) change; results were consistent in mixed‐effects linear regression models accounting for repeated measurements. PA had no impact on MUO indicators, albeit studies were scarce ( n = 4). Promoting PA is a promising strategy against childhood OV/OB. Future research should focus on elucidating its role in MUO prevention.