Reciprocal and authoritarian filial piety beliefs have been shown to have distinct relationships with psychological development and well-being. Such beliefs provide an important foundation for parent–child relationships in Chinese families. However, the literature remains unclear about the mechanism through which filial piety contributes to individuals’ well-being. Because researchers have identified cognitive flexibility as a crucial factor in family contexts and demonstrated that it is associated with individuals’ well-being, the present study aimed to examine the mediating role of cognitive flexibility in the relationship between filial piety and Chinese young adults’general mental health (i.e., self-esteem, life satisfaction, and mental wellness). A total of 455 college students from Taiwan participated in the survey. Structural equation modeling yielded the following findings: (a) Reciprocal filial piety was positively associated with cognitive flexibility and authoritarian filial piety was negatively associated with cognitive flexibility; (b) cognitive flexibility contributed positively to life satisfaction, self-esteem, and mental wellness; and (c) cognitive flexibility mediated the relationship of the two filial piety beliefs with life satisfaction, self-esteem, and mental wellness. These findings indicate that the two filial piety beliefs, which reflect different parent–child relationship quality nurtured in family contexts, could relate to individuals’ flexible mindsets.