This study comprised a meta-analysis of the relationship between learning engagement and learning outcomes in online learning in higher education. The effect sizes of 175 samples were extracted from 34 eligible studies published from January 2010 to March 2022. First, the relationship between learning engagement and learning outcomes was g =0.430, indicating a small-to-medium effect size. Although learning engagement has been reported as a strong indicator of learning outcomes in online learning, learning engagement showed a small-to-medium effect size. Second, there was no statistical difference among behavioral, cognitive, emotional, and general engagement in the effect sizes of the relationship between learning engagement and learning outcomes. Third, in terms of the type of learning domains, the effect size in the affective domain was larger than the cognitive and behavioral domains. Lastly, we found a large effect size for graduate students in the relationship between engagement and learning outcomes followed by undergraduates and adult learners.