To describe treatment outcomes of children and adolescents enrolled in the Pediatric Obesity Weight Evaluation Registry, a consortium of multicomponent pediatric weight management programs in the US. This multicenter prospective observational cohort study, established in 2013, includes youth (2-18 years of age) with obesity enrolled from 31 Pediatric Obesity Weight Evaluation Registry (POWER) sites over a 2-year period and followed up to 12 months. Weight status was evaluated by the percentage of the 95th percentile for body mass index (%BMIp95). Associations of weight status outcomes with patient characteristics and program exposure were analyzed with multivariable mixed effects modeling. We included 6454 children and adolescents (median age, 11 years; IQR, 9-14 years; 53% white, 32% Hispanic; 73% with severe obesity) who were enrolled in POWER. Median changes in %BMIp95 for this cohort were −1.88 (IQR, −5.8 to 1.4), −2.50 (IQR, −7.4 to 1.8), −2.86 (IQR, −8.7 to 1.9), at 4-6, 7-9, and 10-12 of months follow-up, respectively (all P < .05). Older age (≥12 years), greater severity of obesity, and Hispanic race/ethnicity were associated with better improvement in %BMIp95. A 5-percentage point decrease in %BMIp95 was associated with improvement in cardiometabolic risk factors. Overall, treatment in pediatric weight management programs is associated with a modest median decrease in BMI as measured by change in %BMIp95. Further studies are needed to confirm these findings, as well as to identify additional strategies to enhance the effectiveness of these multicomponent interventions for youth with severe obesity. ClinicalTrials.gov: NCT02121132.