BACKGROUND: As China undergoes a rapid demographic shift toward population aging, a critical challenge has emerged for healthy aging policy: how can intergenerational support from adult children be leveraged to maintain and improve the functional ability of older adults? Drawing on nationally representative data, this study investigates the association between such support and the intrinsic capacity of older adults, and explores the pathways through which it operates. METHODS: This study utilizes data from the 2015, 2018, and 2020 waves of the China health and retirement longitudinal study (CHARLS). A multidimensional index of intergenerational support from adult children is constructed, incorporating financial support, emotional closeness, and caregiving. Two-way fixed effects models are employed to estimate the impact of such support on the intrinsic capacity of older adults. Furthermore, a mediation analysis is conducted-using the bootstrap method-to examine potential pathways through social participation, activities of daily living (ADL), and instrumental activities of daily living (IADL). RESULTS: The empirical findings indicate that all three forms of intergenerational support from adult children-financial, emotional, and caregiving-have significant positive effects on the intrinsic capacity of older adults, with caregiving showing the strongest impact. the effects vary across subgroups defined by urban-rural residence, educational attainment, and co-residence status, suggesting substantial heterogeneity. Mediation analysis reveals that social participation partially mediates the effect of financial support (accounting for 14.63% of the total effect), while ADL and IADL explain 60.28% and 53.90% of the effect of caregiving support, respectively. CONCLUSION: intergenerational support from adult children significantly enhances the intrinsic capacity of older adults by promoting social engagement and maintaining functional ability. To advance healthy and active aging, policy efforts should adopt a function-oriented approach that strengthens both family-based support systems and community care infrastructure, while fostering cross-generational resource sharing and coordinated support.