Objective: To examine the potential association between exclusive breastfeeding and its duration on physical fitness (PF) components during childhood. Materials and Methods: A random sample of 5,125 dyads children and their mothers was evaluated. With the use of a standardized questionnaire, telephone interviews were carried out for the collection of maternal lifestyle factors (e.g., breastfeeding and its duration, etc.). Data from five PF tests (e.g., vertical jump, standing long jump, small ball throw, 30-m sprint, and 20-m shuttle run) were used to assess lower and upper body strength, speed, and cardiorespiratory fitness (CRF). Linear and logistic regression models were estimated and adjusted for children's body mass index (BMI) and birth weight, and parental factors (prepregnancy BMI, gestational weight gain, gestational age, pregnancy in vitro, parity before, and educational level). Results: Among boys, exclusive breastfeeding was favorably associated with CRF (b = 0.07), lower body strength (b = 0.41), upper body strength (b = 0.10), and speed (b = -0.11). Also, among girls, we found a favorable association between exclusive breastfeeding and CRF (b = 0.07), lower body strength (b = 0.47), upper body strength (b = 0.10), and speed (b = -0.11). All of the associations remained significant after adjusting for several potential confounders. With the exception of speed test in girls, children who were exclusively breastfed ≥6 months had 10-40% increased odds for average/high performances in PF tests in comparison with those who were breastfed <1 month. Conclusions: Exclusive breastfeeding ≥6 months had a favorable influence on PF test performances in childhood. It seems that exclusive breastfeeding could play a significant role in children's future health.