This meta-analytic review study examined the effects of out-of-school learning (OSL) activities on student attitude and motivation by combining the results of experimental studies conducted between 1990 and 2020. Out of the 1272 studies identified through the literature search, the study selected 46 studies that yielded 47 effect sizes. The effect sizes were combined under a random-effects model to obtain a mean effect for each meta-analysis. The results suggested that OSL practices exert a moderate effect on student attitude (g = 0.525, 95% CI [0.353, 0.704]) and motivation (g = 0.675, 95% CI [0.389, 0.961]), through considerable heterogeneity. Further analysis showed that geographical locations and intervention group size in studies on attitude and geographical locations, OSL structure, and publication year in studies on motivation significantly contributed to effect size variability. Some limitations include publication bias in the meta-analysis on attitude and the few studies on motivation included in the analysis.