People with childhood-onset disabilities face unique physical and social challenges in adulthood. Exercise interventions may improve physical performance in children, but there is a lack of research on adults. To describe studies that investigate exercise interventions and to evaluate the quality of physical performance outcome measures for adults with childhood-onset disabilities. Eligible studies reported on exercise interventions for adults (ages 16+) with cerebral palsy, spina bifida, or acquired brain injuries. Only randomized controlled trials published in English from 2008 to 2019 were included. MEDLINE, CINAHL, PEDro, EMBASE, and Cochrane Central Register of Controlled Trials were searched. Two reviewers independently screened studies and abstracted data. This scoping review included 4 trials reporting on cerebral palsy only. Three strength training programs found significant improvements in gait, and one mixed training program found significant improvements in strength and fitness. Only two outcome measures used are valid/reliable for adults (6 Minute Walk Test and Borg-20 Grades). Certain interventions may improve physical performance, but there is a lack of research on appropriate exercise interventions and physical performance outcome measures for adults with childhood-onset disabilities. Different exercise interventions should be investigated using larger sample sizes and outcome measures should be standardized.