BACKGROUND: The increasing longevity of people with intellectual disability creates a need for a healthy-ageing perspective, translated into evidence-based interventions in this multi-morbidity group. Accordingly, the aim of this scoping review was to identify, summarise and analyse the empirical research on healthy ageing in older adults with intellectual disability. METHODS: This review was based on the PRISMA 2020 guidelines for Scoping Reviews (PRISMA-ScR) and a PICO protocol (Patient/population, Intervention, Comparison/control, and Outcome). Empirical studies in English were included if they concerned older adults with intellectual disability with an average age of at least 45 and were based on a clearly expressed healthy-ageing perspective. An information specialist conducted a search in 11 databases with no geographical or temporal restrictions. Two independent researchers performed study selection, quality assessment and data extraction. Disagreements were resolved in consultation with a third researcher. A textual narrative synthesis was based on PICO domains and the seven research questions. RESULTS: The 11 studies were all from developed countries and had different designs: qualitative, mixed-method and one systematic review. Only three studies highlighted the term "healthy ageing", most used synonymous terms. Eight studies focused on healthy ageing on the individual level, three on the organisational and societal level. The intervention studies in the systematic review were mainly nonrandomised, concerned interventions varying in intensity and duration, considered different research questions and employed different outcome measures. CONCLUSIONS: The findings highlight a major knowledge gap concerning evidence-based interventions with a healthy-ageing perspective in the case of older adults with intellectual disability. There is an urgent need to initiate healthy-ageing studies in developing countries, where such people are even more vulnerable to stigma and discrimination than those in developed countries. Our findings confirm the need to scale up healthy-ageing interventions in line with the WHO's ambition to develop evidence-based approaches to optimise the functional capacity of all older people, including older adults with intellectual disability, by 2030. REGISTRATION: The study is registered in the International Prospective Register of Systematic Reviews (PROSPERO), CRD42022337211 (13 June 2022).