BackgroundThe relationship between adult happiness and income has been a topic of extensive discussion. However, among children and adolescents, who are not directly engaged in economic activities, the relationship between household income over time and happiness is more complex and remains less explored. MethodsWe used nationally representative data from the China Family Panel Study (CFPS) from 2012 to 2018. The analytic sample consisted of 3,607 Chinese adolescents aged 10 to 19 years in 2018. Using an ordinary least squares model, we investigated the associations of 2-year (2016–2018), 4-year (2014–2018), and 6-year (2012–2018) household income mobility (i.e., upward mobility and downward mobility) with adolescents’ subjective well-being (i.e., happiness and depression) in 2018. We further explored the potential mediating effects of parental care on these associations and whether they were moderated by adolescent age, adolescent sex, and initial household economic status. ResultsWe found that upward mobility in household income was associated with decreased subjective well-being and parental care mediated this association. Furthermore, we found that the effects of upward mobility on adolescent subjective well-being varied by age, sex, and initial household economic status. Additionally, downward income mobility did not significantly impact adolescents’ subjective well-being. ConclusionOur findings emphasized that economic progress and upward mobility should not come at the expense of parental care, as this would decrease adolescents’ subjective well-being. Collaboration between the government and families is crucial to address the conflicts between work and family responsibilities, ensuring that parents are available and supportive to their children.