Adoption of primary care interventions to reduce childhood obesity is limited. Progress in reducing obesity prevalence and eliminating disparities can be achieved by implementing effective childhood obesity management interventions in primary care settings. To examine the extent to which implementation strategies supported the uptake of research evidence and implementation of the Connect for Health pediatric weight management program. This quality improvement study took place at 3 geographically and demographically diverse health care organizations with substantially high numbers of children living in low-income communities in Denver, Colorado; Boston, Massachusetts; and Greenville, South Carolina, from November 2019 to April 2022. Participants included pediatric primary care clinicians and staff and families with children aged 2 to 12 years with a body mass index (BMI) in the 85th percentile or higher. Pediatric weight management program with clinician-facing tools (ie, clinical decision support tools) and family-facing tools (ie, educational handouts, text messaging program, community resource guide) along with implementation strategies (ie, training and feedback, technical assistance, virtual learning community, aligning with hospital performance metrics) to support the uptake. Primary outcomes were constructs from the Reach, Effectiveness, Adoption, Implementation, Maintenance (RE-AIM) Framework examined through parent, clinician, and leadership surveys and electronic health record data to understand the number of children screened and identified, use of the clinical decision support tools, program acceptability, fidelity to the intervention and implementation strategies, and program sustainability. The program screened and identified 18 333 children across 3 organizations (Denver Health, 8480 children [46.3%]; mean [SD] age, 7.97 [3.31] years; 3863 [45.5%] female; Massachusetts General Hospital (MGH), 6190 children [33.8%]; mean [SD] age, 7.49 [3.19] years; 2920 [47.2%] female; Prisma Health, 3663 children [20.0%]; mean [SD] age, 7.33 [3.15] years; 1692 [46.2%] female) as having an elevated BMI. The actionable flagging system was used for 8718 children (48%). The reach was equitable, with 7843 children (92.4%) from Denver Health, 4071 children (65.8%) from MGH, and 1720 children (47%) from Prisma Health being from racially and ethnically minoritized groups. The sites had high fidelity to the program and 6 implementation strategies, with 4 strategies (67%) used consistently at Denver Health, 6 (100%) at MGH, and 5 (83%) at Prisma Health. A high program acceptability was found across the 3 health care organizations; for example, the mean (SD) Acceptability of Intervention Measure score was 3.72 (0.84) at Denver Health, 3.82 (0.86) at MGH, and 4.28 (0.68) at Prisma Health. The implementation strategies were associated with 7091 (39%) uses of the clinical decision support tool. The mean (SD) program sustainability scores were 4.46 (1.61) at Denver Health, 5.63 (1.28) at MGH, and 5.54 (0.92) at Prisma Health. These findings suggest that by understanding what strategies enable the adoption of scalable and implementation-ready programs by other health care organizations, it is feasible to improve the screening, identification, and management of children with overweight or obesity and mitigate existing disparities.