We aimed to further the understanding of maternal depressive symptoms on temporal dynamics of child emotion regulation by applying the process model of emotion regulation to preschoolers and incorporating insights from children’s moment-to-moment emotional expressions. Following 108 mother–child dyads (57 girls; 72 mothers identified as White, 23 mothers as Black or African American, 10 mothers as multi-racial, 3 mothers did not report their race) from child age three (T1; Mchild age = 3.23; SD = 0.19) to four years old (T2; Mage = 4.21; SD = 0.15), we asked whether T1 maternal depressive symptoms predicted T2 boys' and girls' faster transitions into and slower transitions out of negative emotion displays when children were frustrated. The results from multilevel Cox Regression models for latencies and durations of emotion displays showed that child gender moderated the associations between maternal depressive symptoms and latencies of child emotion displays for sadness but not anger. Higher levels of maternal depressive symptoms predicted faster transitions into sadness only for girls but not for boys. The findings suggested that girls of mother with elevated depressive symptoms showed impairment in antecedent-focused emotion regulation of sadness.