The operating environment of multinational corporations (MNC) is multilingual, adding significant complexity to knowledge-sharing interactions between employees. In this paper, we explore how knowledge sharing in MNCs is influenced by code switching, or shifting between languages during interaction. Previous international business research has mostly described code switching as a behavior that has a negative impact on knowledge sharing by creating distrust and exclusion. Our case study of a major Finnish MNC from the perspective of faultline theory shows that in situations where organizational norms and routines help limit the potential impacts of code switching on subgroup formation and inter-subgroup animosity, it can also aid knowledge sharing by (i) supporting the development and maintenance of key technical vocabulary, (ii) enhancing inclusion in knowledge-sharing interactions, and (iii) supporting knowledge contextualization processes. Thus, code switching is not necessarily just a form of linguistic interference, but it can also be intended—and often functions—as a strategic behavior that draws on multiple languages to build efficient and successful knowledge-sharing interactions.