Aim: To summarize current evidence on the effects and reach of leisure-time physical activity (LTPA) interventions among children and adults with cerebral palsy (CP). Method: Systematic searches were conducted in PubMed, CINAHL, and Google Scholar to identify randomized controlled trials (RCTs) of LTPA interventions in CP. Data from eligible studies were extracted for qualitative synthesis. Results: Forty-nine studies enrolled a total of 1513 participants (mean [SD] age 13y [7y], range 5–43y; 818 males, 655 females, 40 not reported) and primarily included ambulatory children. RCTs underrepresented adults and people in Gross Motor Function Classification System (GMFCS) levels IV and V. Forty-one studies reported at least one favorable benefit from LTPA. Benefits included improvements to musculoskeletal strength, cardiorespiratory fitness, quality of life, spasticity, participation, and core aspects of physical function. Regarding reach, only 34% of people that were contacted to participate enrolled within a study. A smaller percentage of participants dropped out from intervention (8%) and follow-up periods (3%). Interpretation: Study findings highlight effective interventions to improve health, fitness, and function. To enhance the reach and generalizability of LTPA trials for CP, future studies should examine how to increase study sample sizes and aim to include a better representation of adults and people in GMFCS levels IV and V. What this paper adds: People with cerebral palsy (CP) may experience improvements in health, fitness, and physical function from leisure-time physical activity (LTPA) interventions. Effective interventions include exercise training, active video games, recreation activities, behavioral coaching, and motor skills training. Interventions that incorporate telehealth technology, behavioral coaching, and community resources may enhance LTPA. Interventions primarily include children in Gross Motor Functional Classification System (GMFCS) levels I to III. Adults, wheelchair users, and those in GMFCS levels IV and V are underrepresented.