Growing pains affect many children, but their underlying mechanisms are not fully understood. Potential contributors include anatomical malalignment and abnormal foot-pressure distribution (FPD). This study evaluated: (1) whether age, sex, and handedness correlate with growing-pain intensity, (2) whether anterior or posterior foot loading predominates in these children, and (3) whether customized plantar insoles improve subjective pain and objective postural or gait parameters. A total of 647 children (ages 3–14 years) underwent baseline stabilometric testing (Freemed platform) and were classified as anterior or posterior loaders. Pain status was recorded (absent, mild, moderate, intense). Custom insoles were prescribed for significant anomalies; 178 children returned for follow-up, including 137 who repeated platform assessments, and 178 who were reassessed for pain. Additional subgroup analyses examined insole compliance (high vs. low) and gait changes (step length, stance width, foot progression angle, single-limb stance, gait velocity). Of the initial 647 children, 87% demonstrated posterior orientation, and 55% reported some level of pain. No significant correlations emerged between pain intensity and age, sex, or handedness. Among the 178 reassessed patients, those with higher insole compliance and posterior orientation showed the greatest pain relief (up to 81.8% improvement), while lower-compliance subgroups reported 54.2–62.5% improvement (P = 0.021). Objective FPD improved in 67.7% of the ‘Posterior + High’ group versus 46.7% of the ‘Anterior + Low’ group (P = 0.043). Gait analysis revealed significant improvements in step length, stance width, single-limb stance, and gait velocity (P < 0.05) among children with baseline pain. Posterior foot loading was prevalent in this cohort, and personalized insole therapy was associated with meaningful improvements in subjective pain reports and quantitative gait parameters. While causality cannot be confirmed by this observational design, the findings suggest that targeted plantar corrections may mitigate growing pains and enhance postural stability.