This study examines the relationship between corporate social responsibility (CSR) and firm value in the context of ownership structure. Specifically, our study explores whether large shareholder and foreign shareholder ownership play an important role in the CSR–firm value relationship. Using a sample of 48 firms listed on the Korea Stock Exchange (KSE) between 2010 and 2014, we find that CSR is positively associated with firm value. We further find that the relationship between CSR and firm value is weaker in firms with high large shareholder ownership than in firms with low large shareholder ownership. However, we find no evidence of the effect of foreign ownership on the relationship between CSR and firm value. This study sheds light on the importance of ownership structure in the relationship between CSR and firm value, suggesting significant implications for academics, practitioners, and policymakers. We contribute to the existing literature by providing empirical evidence on the effect of ownership structure on the CSR–firm value relationship. Policymakers may consider these results in implementing their policies that can enhance CSR activities.