Although previous studies have confirmed the impact of parental marital relationships on children’s well-being, few studies have examined their effect on bullying among migrant children. Based on the China Education Panel Survey data, this study used regression analysis and mediation effect methods to analyze this association and its mechanisms. The sample included 1,513 migrant children from diverse ethnic backgrounds. Results showed that a close parental marital relationship significantly reduced migrant children’s bullying, while frequent parental quarrels increased bullying, with the effect persisting over a year. Moreover, teacher-student and peer relationships played critical mediating roles in this dynamic. These findings have important implications for enhancing migrant children’s well-being as well as social work practice.