Given that mother plays the main nurturing role in a family unit and their unique influence on children's development, the current study aimed to examine the influence of maternal phubbing on children's problematic media use and the independent and interactive moderating role of children's negative affectivity and effortful control. Participants were 1986 children aged 3 to 6 years in Shanghai, China. Their mothers were asked to complete a series of questionnaires including parental phubbing scale, problematic media use measure, and child behavior questionnaire. To investigate the moderating influence of children's negative affectivity and effortful control, hierarchical linear regression analyses were conducted using SPSS 24.0. Simple slopes analyses and the Johnson-Neyman technique were further used to depict moderation effects. Maternal phubbing was associated with higher levels of problematic media use in preschool children (β = 0.18, p <.001, [0.14, 0.22]). Children's negative affectivity acts as a risk factor, exacerbating the adverse effects of maternal phubbing on children's problematic media use (β = 0.05, t = 2.69, p < 0.05), whereas children's effortful control acts as a protective factor, buffering the link between maternal phubbing and children's problematic media use (β = -0.10, t = -5.00, p < 0.001). These results suggest that interventions seeking to promote appropriate digital development in preschoolers should take the child's temperament into account and be complemented by active parental mediation and involvement.