Diaryliodonium salts are an important class of hypervalent iodine reagents, widely used as aryl transfer reagents, benzyne precursors, and halogen bond donors in organic synthesis. They also function as photoacid generators and show antibacterial activity. Herein, we report a highly atom-economical strategy for the efficient synthesis of both symmetric and unsymmetric diaryliodonium salts at room temperature, using the readily available (phenyliodonio)sulfamate as a reagent and hexafluoroisopropanol as the solvent. This method demonstrates good functional group compatibility and is scalable to the gram scale. Furthermore, anion exchange enabled the synthesis of commercially available photoacid generators, highlighting the potential of this approach as a viable route for producing photoacid generators. Moreover, sulfamate-containing diaryliodonium salts can react with phenols, amines, and chloride, enabling direct access to the corresponding arylated products.