BACKGROUND The basis of self‐perceived physical competence is built in childhood and school personnel have an important role in this developmental process. We investigated the association between initial self‐perceived physical competence and reported leisure‐time physical activity (LTPA) longitudinally in 10‐, 12‐, and 15‐year‐old children. METHODS This longitudinal follow‐up study comprises pupils from an elementary school cohort (N = 1346) in the city of Turku, Finland (175,000 inhabitants). The self‐perceived physical competence (fitness and appearance) and LTPA data were collected with questionnaires. The full longitudinal data were available from 571 pupils based on repeated studies at the ages of 10, 12, and 15 years in 2004, 2006, and 2010. We analyzed the association of self‐perceived physical competence and LTPA using regression models. RESULTS Self‐perceived physical competence was positively associated with LTPA at all ages (10 years p < .05, 12 years p < .0001, 15 years p < .0001). Increase in the self‐perceived physical fitness scores was likely to associate with higher LTPA at each age point (10 years [odds ratio, OR] = 1.18, 95% confidence interval, CI: 1.09‐1.27; 12 years [OR] = 1.27, 95% CI: 1.18‐1.37; and 15 years [OR] = 1.28, 95% CI: 1.19‐1.38). CONCLUSIONS Self‐perceived physical competence is associated with LTPA in children and adolescents, and the association is strengthened with age.