Purpose: The prevalence of bruxism in children varies considerably. The purpose of this study was to synthesize evidence of the prevalence of bruxism in Brazilian children and consider how proportions differ between genders, assessment approaches, and geographical regions. Methods: A search was conducted using five databases and in gray literature. Two independent investigators selected the studies and extracted data. The risk of bias was assessed via the Joanna Briggs Institute tool for studies on prevalence. The certainty of the evidence was evaluated using Grading of Recommendations Assessment, Development, and Evaluation (GRADE). Results: Twenty-two cross-sectional studies were included after a two-step selection. Overall, 13,076 children from all regions of the country were assessed. The risk of bias ranged from high to low. Data were pooled in a random-effect model and resulted in an overall prevalence of sleep and awake bruxism of 25.8 percent (95 percent confidence interval [95% CI] equals 22.2 to 29.4; I2 equals 96 percent; prediction interval equals 0.07 to 0.44) and 20.1 percent (95% CI equals 18.0 to 22.3; I2 equals 30 percent; prediction interval equals 0.18 to 0.22), respectively. Subgroup and sensibility analysis showed distribution similarity between genders (P=0.96), assessment approaches (P=0.88), and geographical regions (P=0.44). Conclusions: "Possible" and "probable" sleep bruxism affects one in four Brazilian children, and there is evidence with a low level of certainty that its prevalence does not vary between genders, assessment approaches, or geographical regions. The distribution of bruxism is still an unknown subject and presumably occurs because of individual rather than regional or collective factors.