In sports, balance ability has been related to game performance and injury prevention. This study’s aims were twofold: (1) to analyze the balance performance of adolescent soccer players from different age groups; and (2) to examine the relationship between players’ age, body composition, balance, and other physical fitness parameters, such as strength and flexibility. In this study, 112 players from the under 15 (U15), under 16 (U16), and under 17 (U17) age groups participated. A one-way analysis of the variance was conducted to investigate differences between groups. Pearson correlations and hierarchical multiple regression were used to explore the relationship between variables. Regarding balance, the older group performed significantly worse in the stability indexes for both legs but significantly better in dynamic balance tests. Height correlated significantly and negatively with balance indicators. Both jumping tasks showed medium to large correlations with the sway indexes (−0.23 > r < −0.51). Although not significantly, body fat negatively affected balance, underlining the importance of monitoring body composition for players’ development. Overall, no substantial relationship was found between static and dynamic balance variables, and therefore, it is crucial to include both as complementary measures while evaluating youngsters’ postural balance.