ABSTRACTObjectiveWe examine the impacts of parental marital happiness on child outcomes. We also examine the potential mediating role of parenting styles in the relationship between marital happiness and children's behavioral outcomes.BackgroundParents' marital happiness lays a crucial foundation for successful parenthood, which contributes to children's positive development. However, scant research has examined the relationship between parental marital happiness and child outcomes in Chinese populations.MethodData from a subsample of 3,258 parents of third‐grade children in Shanghai and Greater Taipei were analyzed (n = 1,285 from Shanghai; 1,973 from Greater Taipei). We conducted hierarchical multiple regression analyses to investigate whether marital happiness is a significant predictor of children's behavioral outcomes, adjusted for four covariates: parent gender, child gender, site, and subjective social status. We also conducted parallel mediation analyses to examine parenting styles as mediators.ResultsOur findings reveal that in both Shanghai and Greater Taipei, marital happiness was positively associated with authoritative parenting style and negatively associated with harsh parenting style. Moreover, marital happiness was significantly associated with children's behavioral outcomes, even after covariates were accounted for. Our parallel mediation analysis reveals that marital happiness had significant direct and indirect effects on children's behavioral outcomes through authoritative and harsh parenting styles.ConclusionOur findings demonstrate the pivotal importance of parental marital happiness in healthy child development.ImplicationsIntervention programs promoting child welfare in Chinese communities should include interparental relations. Public resources should raise awareness of marital happiness and offer guidance and support for high‐quality relationships.