Objectives <p>This longitudinal study investigated the mediating roles of children’s emotion regulation and lability-negativity in the relationship between mindful parenting and child internalizing problems, with a focus on maternal and paternal differences.</p> Method <p>Participants included 341 parent–child dyads from diverse socio-economic backgrounds in Guangzhou, China, with data collected at two time points, 3&#xa0;months apart. The parents, 341 mothers (<i>M</i>_<i>age</i> = 33.64&#xa0;years; <i>SD</i> = 5.36) and 341 fathers (<i>M</i>_<i>age</i> = 35.69&#xa0;years, <i>SD</i> = 5.32) of children (<i>M</i>_<i>age</i> = 60.48&#xa0;months, <i>SD</i> = 0.62) completed self-report measures of mindful parenting at Time 1, children’s emotion regulation at Time 2, and children’s internalizing problems at both Time 1 and Time 2.</p> Results <p>The results revealed that both maternal and paternal mindful parenting predicted fewer internalizing problems in children, but through different mechanisms. For mothers, maternal mindful parenting was associated with better emotion regulation in children, which in turn was linked to fewer internalizing problems. For fathers, paternal mindful parenting not only enhanced emotion regulation but also reduced lability-negativity in children, both contributing to lower internalizing problems. In a combined family model, paternal mindful parenting remained a significant predictor of lower lability-negativity and fewer internalizing problems, while maternal effects were not significant.</p> Conclusions <p>These findings underscore the importance of considering parental gender in understanding the pathways through which mindful parenting influences child’s mental health. The study provides evidence for the development of tailored interventions that address the specific contributions of both mothers and fathers to enhance children’s emotional well-being.</p> Preregistration <p>This study is not preregistered.</p>