The Russia–Ukraine war has challenged our understanding of corporate social responsibility (CSR). Whereas CSR is traditionally associated with business self-regulation that benefits business and society, the conflict has revealed new forms of what we call “partisan CSR.” Based on comprehensive data from Fortune Global 500 firms, this study discovers that in particular Western, but also some non-Western, corporations have engaged in partisan CSR activities, ranging from (1) strengthening Ukraine’s economy, to (2) enhancing security and protection for Ukrainian citizens, (3) providing (...) military support, (4) weakening Russia’s economy, and (5) supporting Ukraine in symbolic ways. By comparison, several mostly non-Western firms, e.g. from Asian countries, have chosen to be “neutral”, while, in some cases, exploiting economic opportunities arising from the conflict. This study also discusses major drivers of these CSR responses, including political climate, resource availability and economic dependency, isomorphism, and regulatory requirements. Our findings suggest a shift from political CSR to partisan CSR, which we expect to become more important with growing geopolitical divides and territorial conflicts. (shrink)