Background: The aim of this systematic review was to summarize the results and assess the methodological quality of studies that analyzed the relation between physical education participation, physical activity, and sedentary behavior in schoolchildren. Methods: Searches were conducted for original cross-sectional and longitudinal observational studies published in Portuguese, English, and Spanish between January 2007 and August 2020, on the PubMed, Web of Science, Scientific Electronic Library Online, Education Resources Information Center, and Scopus databases. Results: A total of 60 articles (68 independent samples) were included in the revision (58 cross-sectional and 2 longitudinal observational studies). With regard to methodological quality, 27%, 52%, and 21% of the studies were classified as high, moderate, and low methodological quality, respectively. Physical activity was analyzed in 93% of the studies (n = 56) and sedentary behavior in 33% (n = 20). The higher frequency of physical education participation was associated with higher physical activity levels (56 of 68 results – 54/65 cross-sectional and 2/3 longitudinal studies) and less sedentary behavior (14 of 24 results), even after stratifying analyses by type and methodological quality. Conclusion: Physical education class participation may contribute to students being physically more active and less likely to engage in sedentary behavior.