A new method for the preparation of fluoroalkylthioethers including trifluoromethylthioether and difluoromethylthioether by iridium(I)-catalyzed deoxgenation of fluoroalkylsulfoxides with dimethyl diazomalonate was developed. In the reaction system, dimethyl diazomalonate was used as reducing reagent and the corresponding fluoroalkylthioethers were produced through oxygen atom transfer from fluoroalkylsulfoxides to diazomalonate. The protocol featuring effective oxygen atom transfer, mild reaction conditions and good functional groups tolerance offers an alternative strategy for the synthesis of fluoroalkylthioethers. A new method for the preparation of fluoroalkylthioethers including trifluoromethylthioether and difluoromethylthioether by iridium(I)-catalyzed deoxgenation of fluoroalkylsulfoxides with dimethyl diazomalonate was developed.