This study examined parental playfulness as a mediator of the association between mothers' emotional difficulties (anxiety, depression) and their children's psychosocial adjustment (externalizing, internalizing, and prosocial behaviours). We also examined the associations between parental playfulness and mothers' supportive / unsupportive reactions to their child's negative emotions. Participants were 197 mothers of children aged 3-8 years, who completed online questionnaires. Mothers' higher levels of emotional difficulties were associated with lower levels of parental playfulness, and these were associated with children's higher levels of externalizing and internalizing symptoms, and lower levels of prosocial behaviours. Parental playfulness mediated the relationship between mothers' emotional difficulties and children's externalizing symptoms. It was also positively related with mothers' supportive reactions to children's negative emotions and negatively related with unsupportive reactions. These findings underscore the importance of parental playfulness to children's emotional adjustment, particularly to externalizing symptoms, and may provide a basis for new parenting interventions.