Background/Objectives: Cerebral palsy (CP) is the most common cause of physical disability in childhood. While gait improvements are often observed during childhood, it remains unclear whether these gains are sustained into adulthood. This study aimed to evaluate the long-term evolution of gait outcomes from childhood to adulthood in individuals with CP who received orthopedic care early in life.

Methods: This retrospective study included 83 adults with cerebral palsy (44 unilateral/uCP, 39 bilateral/bCP; GMFCS I–III) who underwent clinical gait analysis in childhood and again as adults (minimum 4 years between visits, n = 249 CGA). Gait was assessed using the modified Gait Profile Score (mGPS) and normalized walking speed (NWS). The effects of life stage (childhood, adolescence, early adulthood, and adulthood) were analyzed using Kruskal–Wallis tests with post hoc comparisons. Individual clinical transitions were quantified from early adulthood to adulthood, with a minimal clinically important difference (MCID) change in mGPS (1.6°) and NWS (0.20 s−1) for improvement or decline.

Results: Longitudinal analysis revealed that while group-average mGPS improved from childhood to adulthood, NWS declined significantly for all patients (p < 0.01). However, individual trajectories from early adulthood to adulthood diverged by CP type. Those with bCP GMFCS II and III had a more frequent clinical decline in mGPS (4/14, 29%), with minimal potential for improvement (1/14, 17%). In contrast, individuals with uCP had less frequent decline (1/17, 6%) and a greater improvement (3/17, 18%).

Conclusions: While significant improvements in gait quality are achieved by early adulthood, substantial clinical decline occurs during adulthood in bCP (GMFCS II–III) patients. These findings highlight the need for lifelong monitoring, with re-evaluation regarding the need for surgical interventions from early adulthood to adulthood in bCP patients with greater motor impairments.