Maintaining subjective well-being (SWB) is a key goal of healthy ageing, but the relationship between productive engagement (PE) and well-being remains unclear. Intrinsic capacity (IC), as defined by the WHO, is central to functional ability. However, the reciprocal relationship between PE and IC and their combined roles in shaping SWB remain underexplored. This study examined the bidirectional associations between PE and IC, and further explored whether IC and PE mediate each other’s longitudinal effects on SWB among older adults in China.

Data from three waves (2011, 2013, and 2015) of the China Health and Retirement Longitudinal Study (CHARLS) were analyzed. The sample consisted of 4,365 adults aged 60 years and older who participated in all three waves. PE was assessed through employment, volunteering, and caregiving activities, while IC was measured across five WHO domains. SWB was assessed by self-reported life satisfaction. Cross-lagged panel models were used to test the bidirectional relationships between PE, IC, and SWB, adjusting for demographic and health covariates. Indirect effects were evaluated using bootstrapping with 5,000 resamples.

A bidirectional relationship between PE and IC was observed. Baseline PE predicted greater subsequent IC ( β = 0.075, p < 0.001), and higher IC predicted increased PE ( β = 0.065, p < 0.001). The association between PE and later SWB operated indirectly through IC ( β = 0.0058, 95% CI : 0.0025–0.0092), while the reverse pathway was not significant. Exploratory subgroup analyses suggested descriptively stronger associations among participants aged ≥70 years and those with IADL limitations.

This study provides evidence of reciprocal longitudinal associations between PE and IC, and suggests that IC may partly link PE to subsequent SWB. These findings suggest that IC may function as both a determinant and an outcome of engagement, and that policies combining opportunities for meaningful participation with capacity-preserving strategies may promote healthy ageing.