Because of the exacerbation of population ageing, more family members are involved in the informal care-giving for older adults with disabilities to cater to their long-term care needs. As informal care-givers are associated with the mental health of the care recipient, this study, based on the theoretical framework of the Actor–Partner Effect, utilises a mixed method composed of quantitative and qualitative strategies to identify the relationship among gender and type of both care-giver and care recipient, and mental health of the recipient and explain its internal mechanism. In the quantitative research, ordinary least squares (OLS) regression results based on the basis of the Chinese Longitudinal Healthy Longevity Survey (CLHLS) data corroborate the existence of actor and partner effects within the care-giving dyad. The qualitative analysis further explains the socially constructed differences in gender role, trust relationship and perception towards filial piety of adult care-givers playing their role in the emergence of the Actor–Partner Effect. Finally, this study proposes a developed Actor–Partner Effect analysis framework, advocating to destigmatise disability and construct social support networks for the older adults with disabilities who receive informal care to promote their mental health based on the reflection of socially constructed gender difference.