BackgroundAs a natural source of support for the elderly, the family is an important channel for achieving a sense of security, happiness, and worthiness in old age. In this study, we analysed the characteristics of intergenerational support in families of centenarians and explored the impact of the number of family generations on intergenerational support.MethodsWe conducted a cross‐sectional survey between April 2020 and January 2021 among 62 elderly people aged 99+ in Rugao, China, one of six ‘longevity cities’ in the world. Assisted by the researchers, centenarians completed questionnaires with details pertaining to general demographics, intergenerational support, and other aspects. We used a logistic regression model to analyse the influence of the number of family generations on intergenerational support that the centenarians received with respect to economic, living, and emotional aspects.ResultsCentenarians were primarily recipients of care in their families, and received intergenerational support mainly for their declined physical functions and limited self‐care ability. The study results revealed that the greater the number of generations comprising the family, the greater was the intergenerational life care and emotional comfort provided for centenarians by the family.ConclusionsIn this study, we found a positive effect of the number of family generations on intergenerational support for centenarians. The government and society should promote the tradition of respecting, caring for, and honouring the elderly while paying close attention to the dynamic changes in the family structure of centenarians in promoting high‐quality and sustainable development of the people, economy, and society.