Background It is common for older people to become grandparents in later life. However, the impacts of grandparenting on their health and well-being remain under-investigated, especially in Chinese society where family is in the core of culture. The current study explored the relationship between grandparenthood and Chinese older people’s health and psychological well-being in Hong Kong. Methods Data was collected from a sample of 1,208 Hong Kong Chinese older people aged 55 and above through a telephone survey conducted in 2019. Participants were grouped into three categories: current grandparents (n = 507), grandparents-to-be (n = 275), and grandparents-not-to-be (n = 426).. Multivariate linear regressions were performed to examine the relationship between grandparenting status and health and well-being outcomes, including self-rated physical health, mental health, resilience, and happiness, while controlling for age, gender, education, marital status, financial status, and physical activity level. Results Bivariate analyses suggested statistically significant differences between health and well-being across the three groups of participants. Regression models showed that, when compared with grandparents-not-to-be, being a current grandparent was associated with a significantly higher level of happiness, while being a future grandparent was associated with significantly higher levels of happiness, resilience, and self-rated physical health.Conclusions The current study offers preliminary insights into the significant relationship between grandparenthood and older adults’ health and well-being. It calls for future studies to further explore the mechanisms behind the benefits of grandparenthood. Grandparenting is a potentially good starting point to build older adults’ capacity to promote healthy ageing.