Parent-child separation due to internal migration is prevalent in China. However, few studies have focused on the associations between different characteristics of parent-child separation and children’s involvement in bullying. We conducted a cross-sectional study among 2,355 fifth-to eighth-grade students in China, using self-reported questionnaires to investigate the associations between children’s bullying involvement (i.e., bullies, victims, bully-victims) and different characteristics of parent-child separation resulting from parental migration. Bivariate and multivariate analyses were conducted to explore these associations. Among all respondents, 17.3% reported being victims of bullying, 3.8% reported being bullies, and 2.7% reported being bully-victims. Compared to children with no left-behind experiences, those with current left-behind experiences were more likely to be victims and bully-victims. Children left behind by parent(s) at the age of three years or younger were more likely to be victims (aOR = 1.66, 95% CI [1.22, 2.25], p = .001), bullies (aOR = 1.88, 95% CI [1.02, 3.52]), and bully-victims (aOR = 2.17, 95% CI [1.04, 4.71]). Children left behind for seven years or longer were more likely to be victims (aOR = 1.49, 95% CI [1.12, 2.00], p = .007), bullies (aOR = 2.03, 95% CI [1.15, 3.69]), and bully-victims (aOR = 2.13, 95% CI [1.06, 4.50]). The identified characteristics of parent-child separation associated with bullying involvement hold implications for parental decisions regarding internal migration, interventions, and policymaking for preventing bullying among left-behind children.