While the body of research on grand challenges (GCs) has grown, our understanding of the role of corporate social innovation (CSI) in tackling exigent GCs, such as the COVID-19 pandemic, is limited. Based on in-depth analyses of four cases of CSI in the services sector during the COVID-19 pandemic, this paper contributes to the GC literature by developing a 3Es framework of the CSI process (i.e., embeddedness, engagement, and enhancement) to illustrate the mechanisms through which exigent GCs can be effectively addressed by firms in the services sector. First, CSI embeddedness in intersectoral partnerships with international organizations based on deep-rooted trust and collective commitment is found to be a fundamental mechanism for efficiently addressing the COVID-19 crisis. Second, CSI engagement through the transformation of existing technology and/or the adaption of existing products/services is found to be an important mechanism for meeting pandemic-induced social needs. Specifically, it is found that leading-edge technologies such as digital platforms can be rapidly repurposed to enable loosely coupled systems that evolve as a new channel to bring together various stakeholders and thus address this urgent GC. Finally, CSI enhancement supported by managerial agility and participatory governance structure plays a crucial role in enabling CSI to function effectively in the context of exigent GCs.