This rapid realist review explored the key components of age-friendly ecosystems that promote community participation among older adults. The study (undertaken in 2021 and updated in 2023) synthesized evidence from 10 peer-reviewed and grey literature databases to identify the underlying mechanisms and contextual factors that shape why, under what circumstances, and for whom an age-friendly ecosystems might be effective as well as the intervention outcomes. A total of 2823 records were initially identified after deduplication. Title and abstract screening produced a potential dataset of 126 articles, reducing to 14 articles after full text screening. Data extraction focused on the contexts, mechanisms, and outcomes of ecosystems for older adults’ community participation. Analysis suggested that age-friendly ecosystems that aim to promote community participation are characterized by the provision of accessible and inclusive physical environments, the availability of supportive social networks and services, and the creation of opportunities for meaningful engagement in community life. The review also highlighted the importance of recognizing the diverse needs and preferences of older adults and involving them in the design and implementation of age-friendly ecosystems. Overall, the study has provided valuable insights into the mechanisms and contextual factors that contribute to the success of age-friendly ecosystems. Ecosystem outcomes were not well discussed in the literature. The analysis has important implications for policy and practice, emphasizing the need to develop interventions that are tailored to the specific needs and contexts of older adults, and that promote community participation as a means of enhancing health, wellbeing, and quality of life in later life.