Objective To ascertain the barriers and facilitators to physical activity (PA) for older adults in Residential Aged Care Facilities (RACFs), from the perspective of residents, staff, and family. Methods A mixed-methods systematic review, underpinned by the Social Ecological Model (SEM). Five databases were searched from inception to May 2024. Data synthesis followed a convergent integrated approach, with relevant quantitative data ‘qualitised’ and synthesised with qualitative data using thematic synthesis. Results This review included 67 studies (40 qualitative, 16 mixed-methods, and 11 quantitative). Thematic synthesis identified 51 key themes (27 facilitators and 24 barriers), spanning all levels of the SEM. Intrapersonal factors (e.g. poor general health) were the most commonly cited barriers ( n = 53 studies), and interpersonal factors (e.g. social support) the most commonly reported facilitators ( n = 55 studies) to PA in RACFs. Discussion An interplay of multi-level factors must be addressed in the development and implementation of strategies to promote PA in RACFs.