A new synthetic method for alkyl sulfones through C-C bond formation between alkenes and tosylmethylphosphonium iodide is reported. A tosylmethyl radical is generated from the phosphonium iodide under irradiation of visible light with the aid of fac-Ir(ppy)(3). It undergoes regioselective 1,2-addition across the carbon-carbon double bond to afford an elongated alkyl radical, which abstracts a hydrogen atom from C6F5SH, producing an alkyl sulfone with one-carbon extension.