Participation in adult education is a crucial component of the active aging framework. However, there have been limited studies exploring the association between participation in adult education and subjective wellbeing among older adults. Furthermore, the underlying mediating and moderating mechanisms in this association have not been extensively investigated. This study aims to explore the mediating roles of physical and digital isolation, as well as the moderating roles of educational level. A sample of 7,602 older adults (M = 70.97, SD = 7.13) was drawn from the 2018 wave of the China Longitudinal Aging Social Survey. Structural equation modeling was employed to test the mediating and moderating roles. The results revealed that participation in adult education is positively associated with higher levels of life satisfaction and lower levels of loneliness among older adults. Both physical isolation and digital isolation play mediating roles in these associations. Moreover, educational level moderates the association between participation in adult education and older adults' life satisfaction and loneliness. The linkages are significant for older adults with lower levels of education, but not significant for those with higher levels of education. These findings contribute to current knowledge and offer practical implications for improving older adults' subjective wellbeing through participation in adult education.