Cyanomethanesulfonyl chloride is used primarily as a sulfonylating agent in organic synthesis, enabling the introduction of the cyanomethanesulfonyl group into various substrates. Its reactivity, stemming from both the sulfonyl chloride and cyano functionalities, makes it valuable in the preparation of sulfonamides and other derivatives, which serve as key intermediates in pharmaceuticals and agrochemicals. It is also employed in the development of dyes and functional materials where such sulfonyl derivatives are required. Due to its high reactivity, it is typically handled under controlled conditions to ensure selective transformations and further functionalization via the cyano group.