Lay summary – Researchers are increasingly recognising that people affected by acquired brain and spinal injuries, along with their families, carers, clinicians, and communities, should be involved in shaping research and services. This involvement can help make interventions more practical, acceptable, and relevant to the places where they will be used. This review looks at how community engagement and involvement has been used in research on acquired brain and spinal injuries in both high-income countries and low- and middle-income countries. By comparing different settings, it aims to understand what helps community involvement work well, what challenges may arise, and how future research can better reflect the needs and experiences of the people most affected.