Abstract: With the changing structure of China’s rural labor force and the transformation of both urban and rural economies, the shift from a “migrant worker economy” to an “entrepreneurship economy” has become an important driving force for promoting high-quality development in county economies. Based on panel data from 1,502 counties in China between 2008 and 2022, this study uses nighttime light data as a proxy for county-level economic development and regards the implementation of the pilot policy for migrant workers returning to their hometowns to start businesses as a quasi-natural experiment. A multi-period difference-in-differences model is constructed to examine the impact of migrant workers’ return-home entrepreneurship on county economic development. The results show that return-home entrepreneurship by migrant workers significantly promotes county economic growth, with the effects being more pronounced in central and western regions and in labor-exporting counties. Mechanism analysis indicates that this effect is mainly realized by improving local farmers’ income levels and enhancing market activity. Accordingly, policy implications include continuously improving the return-home entrepreneurship policy system in line with regional differences, strengthening the core strategic position of return-home entrepreneurship, establishing a long-term mechanism of “entrepreneurship-driven income growth”, and optimizing both the soft and hard environments in counties to promote steady economic growth.