Background/aim: The aim was to assess the differences between physical activity and physical fitness in obese, overweight, and normal-weight children. Materials and methods: The cross-sectional study was accomplished using cluster sampling method at 3 Lithuanian schools. An analysis of anthropometric data for 532 Lithuanian children was performed. Height, weight, waist and hip circumferences, and skinfold thickness were measured. Body mass index, waist-to-hip ratio, and body fat percentage were calculated. The Youth Physical Activity Questionnaire and a 6-min walk test (6MWT) were administered to evaluate physical activity and physical fitness. Maximal oxygen consumption was calculated to assess the children's aerobic capacity. Correlations among anthropometric data, 6MWT-walked distance, and moderate-vigorous physical activity duration were analyzed. Results: The study showed that 20.1% of the studied children were obese or overweight. They engaged in moderate-to-vigorous physical activity 22.4 min less per day and walked 50.9 m less on average during a 6-min test than normal-weight children. Physical fitness parameters correlated with daily moderate-vigorous physical activity duration and with most of the children's anthropometric parameters. Conclusion: Obese and overweight children were less physically active and had lower physical fitness than normal-weight children. The findings underline the need for interventions to increase physical activity and improve fitness in obese and overweight children.