The relationship between mother and child emotion regulation (ER) is widely researched, but fewer studies have investigated explanatory variables or those affecting the strength of this link. Background/Objectives: The present study focused on maternal play behavior, considered as an explanatory mechanism between mother and child ER. In addition, the study explored the moderating role of paternal empathy in the association between maternal emotion regulation (ER) and maternal play behavior. Methods: This present cross-sectional study involves 103 mothers and their husbands (the children's fathers), with at least one child between the ages of 3 and 6 who is typically developed. Results: Our findings show that maternal play behavior mediates the relationship between maternal cognitive reappraisal (CR), expressive suppression (ES), and child ER. Regarding the moderating role of paternal empathy, lower levels moderate the association between ER and maternal play behavior. Conclusions: Our findings highlight the importance of maternal play behavior as an explanatory variable between maternal and child outcomes and, concomitantly, of paternal variables, such as empathy, in supporting maternal play behavior when it comes to achieving better child outcomes.