ObjectivesThis study explored the effect of the interaction between intrinsic capacity and social support on the activities of daily living in the older adults. MethodsA total of 3,124 older adults participated in the study. Data on the assessment of intrinsic capacity as well as activities of daily living (ADL) and social support were collected. The latent growth curve model (LGCM) was used to examine the effect of the interaction between social support and intrinsic capacity on the activities of daily living in the older adults. ResultsA total of 3,730 older adults were included at baseline, and 3,124 older adults completed the 4-year follow-up. The ADL score of the older adults showed a significant downward trend with time over 4 years (β=-0.115, P<0.05). In the elderly population with high intrinsic capacity, the ADL of individuals with low levels of social participation decreased significantly over time (β=-0.114, P=0.012). In the elderly group with low intrinsic capacity, the ADL of individuals with low levels of social participation (β=-0.245, P=0.005) and high levels of life care (β=-0.167, P=0.001) decreased significantly over time. ConclusionThis is the first longitudinal study to explore the effects of interactions among intrinsic capacity, social participation and family support on the trajectory of ADL in the older adults from the perspective of the life course. Social participation can effectively improve functional ability of older adults with low intrinsic capacity. Life care is beneficial for maintaining the functional ability of older adults with intact intrinsic capacity, but it accelerates the deterioration of the functional ability of older adults with low intrinsic capacity.