A reaction of an iododifluoromethylphosphonium salt with unactivated alkenes mediated by peri-xanthenoxanthene under blue-light irradiation is described. The reaction proceeds via activation of the carbon-iodine bond to generate (phosphonio)difluoromethyl radical cation, which attacks the double bond with subsequent quenching by the iodine. The intermediate phosphonium salts are easily hydrolyzed, furnishing products of iododifluoromethylation of alkenes.