<p>Employing a moderated parallel mediation model, this study investigated the influence mechanism of parental smartphone addiction on children’s social avoidance among 1586 parent-child dyads (<i>M</i>_<i>age</i> =51.19 months, <i>SD</i> = 13.49) in Shanghai, China. The results revealed that: (1) maternal smartphone addiction positively predicted children’s social avoidance; (2) mother-child closeness and mother-child conflict significantly mediated the relationship between maternal smartphone addiction and children’s social avoidance, accounting for 13.33% and 45% of the total effect, respectively; (3) mother-child conflict moderated the relationship between paternal smartphone addiction and children’s social avoidance, with the association being significant only when mother-child conflict was below 1.65 SD. Both mother-child conflict and mother-child closeness moderated the relationship between father-child closeness and children’s social avoidance, with the association being significant only when mother-child conflict was above 0.002 SD and mother-child closeness was below − 1.40 SD. These findings suggest that enhancing parent-child closeness and reducing parent-child conflict may buffer the adverse effects of parental smartphone addiction on children’s social avoidance.</p>