Problematic media use among preschoolers is a growing concern. This study investigates the relationship between mother phubbing and problematic media use in preschoolers, examining the mediating role of child screen preference and the moderating effect of extraversion. 772 mothers (Mean[subscript age] = 34.13 years) with preschool-aged children from Shanghai completed an online survey. The study found a significant positive correlation between mother phubbing and child problematic media use, mediated by the child's screen preference. Extraversion moderated the link between mother phubbing and child screen preference, with the relationship weakening as the child's extraversion increased. These findings highlight the complex interplay between parental behaviour, child characteristics, and media use patterns in early childhood, emphasizing the need for tailored interventions considering both environmental and individual factors.