Foreign direct investment (FDI) has become a significant source of funding for enterprises, particularly among family businesses in China in recent years. This paper examines the impact of FDI inflow on corporate social responsibility (CSR) through the lens of the spillover effect of FDI and the equity balance theory, utilizing data from listed family businesses in China from the year 2010 to 2019. Our findings indicate that: (1) FDI inflow positively influences the CSR of family businesses; and (2) the equity balance rate enhances the positive effect of FDI on the CSR of family businesses.