This study investigated the association between social integration and utilization of essential public health services among internal migrants. Data were from the 2017 China Migrants Dynamic Survey. Social integration was measured through four dimensions: economic integration, structural integration, sociocultural adaptation, and self-identity. Multilevel logistic regressions were used taking into account heterogeneity in the level of regional development. The utilization of health records and health education was less than 40% and varied widely across regions. Social integration was related to a higher likelihood of utilization of health records and health education. Moreover, sociocultural adaptation had a stronger effect on the utilization of health records in developed regions than in developing regions, and structural integration was strongly and positively related to the utilization of health education in developed regions. Hence, it appears that the relationship of some dimensions of social integration and utilization of essential public health services is moderated by the level of economic development. Promoting structural integration and sociocultural adaptation could strongly improve utilization of essential public health services in developed regions.