Introduction: Mandible positioning can cause global postural adaptations. Physiotherapists and dentists try to relate the mandible position and chewing side to plantar support; however, this indication is uncertain. Objectives: To check the existence of a relationship between mandible position, preferred chewing side, age, and plantar support in children. Materials and methods: This is a cross-sectional study with 93 children, aged between 4 and 11 years. Photogrammetry was used to confirm the mandibular positions (centralized, to the right, and to the left), and baropodometry was used to measure plantar support. The mandibular displacement distance to the right and left was evaluated, and the plantar support in the three mandibular positions was compared as a function of age (4–7 and 8–11 years) and preferred chewing side. Results: There was greater mandibular displacement in left laterality [13 (9–19) cm] compared to right laterality [7 (3.50–12.00) cm] (p < 0.01). Mandibular position did not alter mean pressure, maximum pressure, or plantar support surface (p > 0.05). With the mandible centralized, higher mean pressure, maximum pressure, and surface area were observed in the left foot (p < 0.01). Older children showed greater mandibular displacement to the left (p < 0.01). No differences were observed for the variables of plantar support as a function of age (p > 0.05) and chewing side (p > 0.05). There was a moderate to strong correlation between age, body mass, height, and plantar surface area (0.63 < r < 0.83; p < 0.05) and between mean and maximum pressures of plantar support (0.58 < r < 0.89; p < 0.05). Conclusion: Mandibular position, age, and preferred chewing side do not influence plantar support in children.