Research on cultural family beliefs and family processes as protective factors of adolescent development is severely lacking in the Chinese culture. Based on 432 Chinese single‐mother families living in poverty in Hong Kong, the relationships among Chinese cultural beliefs of familism, adolescent perceived maternal sacrifice, and psychological competence (indexed by a clear and healthy identity, cognitive competence, and a positive future outlook) were examined. Results showed that adolescents' perceived maternal sacrifice mediated the influence between maternal Chinese cultural beliefs of familism and the psychological competence of adolescents raised in poor single‐mother families in Hong Kong. The present study underscores the importance of cultural family beliefs and parental sacrifice on nurturing adolescent psychological competence in Chinese single‐mother families living in poverty, which contributes to the construction of a family resilience model applicable to Chinese communities.