© 2020 Sports Medicine Australia Objectives: Global health guidelines suggest that youth should accumulate at least 60 min of daily, moderate-to-vigorous-intensity physical activity (MVPA). The relationship between meeting physical activity (PA) guidelines and motor competence (MC) in youth is relatively unknown. This study assessed levels of MVPA and MC among socially vulnerable youth and determined if meeting the PA guidelines was associated with MC. Design: Cross-sectional. Methods: A total of 1017 youths aged 3–14 years from three schools participated in the study. Participants wore accelerometers for seven consecutive days to assess PA. Motor competence was assessed using the Test of Gross Motor Development, 2nd Edition and the Körperkoordinationstest für Kinder. MVPA and MC were compared by sex and school levels (preschool, elementary school and middle school). Binary logistic regression models examined the predictive power of meeting PA guidelines and age on MC. Results: The prevalence of meeting PA guidelines declined across school levels among both girls (72% in preschool to 21% in middle school, p < 0.001) and boys (84% in preschool to 57% in middle school, p < 0.001). MC levels were low and also declined across age in both sexes (p < 0.001). During preschool, age (older) was a consistent predictor of low MC, independently of meeting PA guidelines. Conclusions: Except for adolescent boys, meeting PA guidelines was not associated with higher MC. Public health policies should focus on the quantity and quality of MVPA within schools and on alleviating the decline in PA and MC across childhood and adolescence, with special attention to girls and disadvantaged families.