The DNA-encoded library (DEL) technology is a new method for discovering hit compounds for target proteins in the pharmaceutical industry. The N-acylsulfonamide functional group has been reported to exhibit various pharmacological activities, and based on this, the demand for a method that allows its introduction into the DEL platform has increased. In this report, a procedure for synthesizing N-acylsulfonamide functional groups applicable to DEL construction was developed in the presence of a copper reagent and water as a nucleophile from simple alkynes or sulfonyl azides, which are widely commercially available. Furthermore, we prove that a new alternative procedure can be used to construct a DNA-encoded library.