<p>Improving the quality of employment among migrant workers is a crucial step in promoting common prosperity. Adolescent migration is a distinctive life experience that exerts profound influences on the labor market. Based on the data from the China Migrants Dynamics Survey and China Family Panel Studies, this study explores the comprehensive effect and mechanisms of adolescent migration on the employment quality of migrant workers. Results show that migration experience during adolescence significantly reduces quality of employment in adulthood. Although migration experience increases wage income, it simultaneously makes work more intense and weakens job stability and welfare security. Quantile regression shows that the negative effect of migration presents a “W”-shaped trend, with a particularly significant influence on migrant workers with medium to low employment quality. Furthermore, there exists a significant inverted U-shaped relationship between cumulative migration duration and employment quality. Mechanism analysis indicates that migration experiences have a negative impact on the long-term educational attainment, cognitive and non-cognitive abilities of migrant workers, thereby reducing their employment quality. Heterogeneity analysis reveals that the negative impact of migration on employment quality does not show significant differences among subgroups of migrant workers with different childhood experiences, gender, age, education, or income. However, there are significant differences among the subgroups of migrant workers in different migration reasons, types, distance, cities and current residence. This study explains the mechanisms affecting the employment quality of migrant workers from the perspective of life course, providing practical guidance and policy references for China to achieve high-quality employment and common prosperity.</p>