Parental self-differentiation from their family of origin has been considered to play a significant role in parenting and ultimately contributes to child development as well. Based on this theoretical and empirical understanding, the present study aimed to examine the effect of fathers’ self-differentiation on the sociality of their young children and to identify the specific mediating pathways along which this influence is transmitted. In particular, this study aimed to test whether marital conflict and paternal participation in parenting serve as a single or a sequential mediator in this process. A self-report online questionnaire was conducted to fathers of children aged 3 to 5, and a total of 242 valid responses were analyzed. Correlational analyses revealed significant relationships among all four core variables. A path analysis showed that the mediation path through paternal parenting participation, as well as the sequential mediation path through marital conflict followed by parenting participation, were significant. In contrast, the single mediation path through marital conflict alone was not significant. Furthermore, the direct path from fathers’ self-differentiation to their children`s sociality was not significant, indicating a complete mediation through the two aforementioned pathways. These findings highlight the critical role of fathers’ parenting participation in mediating the relationship between their self-differentiation and their children’s social development. Implications for father-focused parent education and intervention programs were discussed.