Background Migrant children refer to rural children who accompany one or both parents to urban area. Empirical evidence showed that compared with their urban counterparts, migrant children had poorer developmental, emotional and psychological health. Method A sample of 1306 migrant children were recruited to examine the characteristics of migrant children and investigate the effects of identity integration, support and socioeconomic factors (e.g. age, gender, type of school, family socioeconomic status, city type) on their subjective wellbeing. Results Children with higher levels of identity integration, social support, family socioeconomic status, who attended public school and who lived in the third‐tiered city of Weihai demonstrated better subjective wellbeing. Social support remained a strong predictor for subjective wellbeing, despite a significant mediating effect of identity integration. Conclusions These results highlight the need for policymakers and practitioners alike to address individual factors pertaining to psychological adjustments, as well as social determinants of subjective wellbeing in the context of migration.