Currently, very few studies have comprehensively investigated how intergenerational relationship quality (IRQ) between older parents and adult children is related to older adults' activity engagement. To fill this gap, this study endeavoured to examine the associations between IRQ and older adults' activity profiles, not only considering the overall IRQ but also different dimensions of IRQ. We also aimed to reveal the different roles of IRQ with son(s) and with daughter(s). This study made use of survey data collected in Yibin City, Sichuan Province of China in 2018 (N = 4,211). We adopted hierarchical cluster analysis to identify activity profiles, and performed multinomial logistic regressions to assess the association between IRQ and the profiles. We identified five activity profiles among older adults: "caregiving-oriented", "employment-oriented", "social withdrawal", "diverse engagement" and "physically active". Those with greater IRQ were more likely to be "caregiving-oriented" and have "diverse engagement" relative to "social withdrawal". It also showed that structural-associational solidarity and affectual closeness were more predictive of the activity profiles, compared to consensual-normative solidarity and intergenerational conflict. Children's gender plays an important role in the relationship between IRQ and activity engagement profiles. Good intergenerational relationships might not narrow down older adults' activity domains, and instead might actually promote their participation in diverse domains. Promoting structural-associational solidarity and affectual closeness was likely to reduce social withdrawal among older adults in China.