Positive paternal involvement during early childhood is important for fostering healthy development. However, mental health conditions, particularly depression, can significantly limit a father's ability to engage constructively. This study explored whether religiosity can act as a resource for fathers, potentially mitigating the adverse effects of depression on their ability to engage in their child’s life. Analyzing survey data from 1147 fathers with children aged two to eight, the study investigated the how religiosity and depression interact across four domains of paternal involvement: engagement, warmth, harsh punishment, and positive control. Hierarchical regression analyses revealed that fathers with higher religiosity scores exhibited more warmth, greater engagement, and higher levels of both harsh punishment and positive control techniques. Fathers with more depression symptoms were associated with more frequent harsh punishment behaviors and lower reports of warmth compared to fathers with less depression symptoms. Notably, a significant interaction effect between depression and religiosity was identified, indicating that fathers with high levels of both depressive symptoms and religiosity were at the greatest risk of engaging in harsh punishment behaviors. These findings suggest that while religiosity may support positive parenting behaviors, it may also intensify the use of harsh punishment among fathers struggling with depression. This highlights the need for targeted interventions to help fathers manage their depression and adopt positive parenting practices.