Background <p>Femoroacetabular impingement affects 14%–17% of young adults; nonoperative physiotherapy has demonstrated outcomes comparable to surgery in selected cohorts. However, age-specific treatment responses remain poorly defined, impeding evidence-based management across age cohorts.</p> Methods <p>We conducted a prospective observational cohort study of 120 participants with femoroacetabular impingement at three specialized centres. Participants were stratified into adolescent (≤ 18 years; <i>n</i> = 60) and adult (19–45 years; <i>n</i> = 60) cohorts, each receiving standardized physiotherapy over six months. The primary outcome was a change in the International Hip Outcome Tool-33 score at six months. Secondary outcomes included Hip Outcome Score subscales, biomechanical measures, and return-to-sport rates assessed at six and 12 months. Statistical analysis employed two-sample t-tests and chi-square tests with a two-sided α = 0.025 for primary outcomes.</p> Results <p>At six months, adolescents achieved significantly higher International Hip Outcome Tool-33 scores (72.4 ± 18.3 vs. 61.8 ± 19.7; difference, 10.6 points (95% CI, 3.2–18.0); <i>p</i> = 0.006 and faster time to clinically meaningful improvement (8.2 ± 4.1 vs. 10.7 ± 5.3 weeks; <i>p</i> = 0.012). Adolescents demonstrated superior Hip Outcome Score Activities of Daily Living (88.3 ± 14.2 vs. 82.1 ± 16.8; <i>p</i> = 0.037), modified Harris Hip Scores (85.7 ± 12.8 vs. 79.3 ± 15.2; <i>p</i> = 0.007), and hip range of motion. Return-to-sport rates favored adolescents at 12 months (89.6% vs. 77.6%). Advantages persisted throughout the 12-month follow-up.</p> Conclusions <p>Adolescent femoroacetabular impingement patients demonstrate superior functional recovery trajectories compared to adults following nonoperative physiotherapy management. These findings support age-stratified treatment algorithms and suggest more favorable prognoses for younger patients pursuing conservative management.</p>