<p>Economic integration is a critical aspect of migrants’ successful inclusion in host societies, yet the influence of life course factors on this process remains underexplored. Using nationally representative data from China, this study examines how childhood left-behind experiences (LBE), defined as being cared for by relatives due to parental migration, influence the economic integration of the new generation of rural-to-urban migrants. The results show that childhood LBE significantly reduces the likelihood of formal employment, lowers wages, increases the incidence of overwork, and decreases the probability of homeownership in destination cities. These negative effects are most pronounced among migrants who have lived in the destination for less than five years. Further analysis identifies three mechanisms through which childhood LBE hinders economic integration: reduced human capital, weakened psychological resilience, and limited social networks. We also find that the impact of childhood LBE varies by its type and timing. In addition, parental educational attainment and educational resources in the place of origin help to moderate these adverse effects.</p>