<p>Children in rural China from father-migrant families may face elevated developmental risks when mothers are also absent. While prior research has documented poorer outcomes among left-behind children with absent mothers, less is known about the additional association of maternal absence within father-migrant families and the relational processes associated with these developmental differences. Drawing on data from 1,082 preschool children in rural China with migrant fathers, this study examines the association between maternal absence and children’s social-emotional development, with parent–child interaction considered as a potential relational pathway. The results indicate that maternal absence is associated with lower levels of social-emotional competence. Mediation analysis further suggests that differences in parent–child interaction are linked to part of this association. Group comparisons across grandparent-based caregiving, community support, and peer interaction show descriptive differences in these patterns across relational contexts. The findings highlight the importance of parent–child engagement and broader relational environments in understanding developmental variation among preschool children in father-migrant families.</p>