Background <p>Sedentary behaviour and physical inactivity contribute to muscle-related decline (e.g., sarcopenia), chronic disease and disability. This study aims to (1) explore nursing home residents’ and staff’s perspectives and experiences regarding interventions addressing sedentary behaviour and physical inactivity; (2) refine a Theory of Change logic model for such interventions in nursing homes.</p> Methods <p>An exploratory qualitative study design. In-person interviews with 14 residents and 12 staff members at two urban nursing homes in China. Data were analysed applying codebook thematic analysis, mapped onto the Ecological Social Theory encompassing individual (micro), organisational (meso), family (exo) and societal (macro) contexts.</p> Results <p>Four themes were identified. (1) Microsystem: individual physical, psychosocial, cognitive, and educational constraints hindered participation in physical activity, while perceived potential for benefit encouraged participation. (2) Mesosystem: social interaction between residents impacted on activity participation both positively (e.g., encouragement) and negatively (e.g., peer pressure). Staff roles were key facilitators by coordinating intervention while insufficient activity management and resources constrained use. (3) Exosystem: family attitudes, support and bonds influenced the decision-making process and residents’ motivation in activities. (4) Macrosystem: sufficient funding was important to provide and sustain activity interventions in nursing homes. Societal ties with the community external to nursing homes boosted residents’ activity engagement. </p> Conclusions <p>Multilevel factors from individual, organisational, family, and societal contexts were identified. A Theory of Change logic model was adapted by enhancing its applicability to specific context while maintaining its general framework. To optimise activity interventions in nursing homes, it is essential to enhance staff roles, refine activity management, leverage social interactions within nursing homes strategically, maintain family involvement, sustain financial input and collaborate with social organisations. Multilevel strategies are crucial for addressing the global challenges of sedentary behaviour and physical inactivity in nursing homes. Adapting the Theory of Change logic model to specific context opens opportunities for tailored application across diverse cultural settings.</p> Clinical trial number <p>Not applicable.</p>