AIM: To determine the proportion of adults with cerebral palsy (CP) using health services and frequency of use, and to explore experiences and perceptions of health services for this population. METHOD: A mixed-methods systematic review was conducted using the Joanna Briggs Institute methodology. Five databases were searched to September 2020. Observational and qualitative studies were included. Two reviewers screened titles, abstracts, and full texts; extracted data; and assessed the quality of included studies. Separate meta-analyses were used to pool the proportion of adults using each service and frequency of use. A meta-aggregation approach was used to synthesize qualitative data. Quantitative and qualitative findings were integrated using the Andersen and Newman Model of health care utilization. RESULTS: Fifty-seven studies (31 quantitative, 26 qualitative) of 14 300 adults with CP were included. The proportion of adults using services ranged from 7% (95% confidence interval [CI]: 2-13%) for urologists to 84% (95% CI: 78-90%) for general practitioners. Incidence of visits ranged from 67 (95% CI: 37-123) hospital admissions to 404 (95% CI: 175-934) general practitioner visits per 100 person-years. Qualitative themes highlighted issues regarding accessibility, caregivers' involvement, health workers' expertise, unmet ageing needs, transition, and health system challenges. INTERPRETATION: Adults with CP used a wide range of health services but faced context-specific challenges in accessing required care. Appropriate service delivery models for adults with CP are required. This review emphasizes a need to develop an appropriate service model for adults with CP to meet their needs.