FeCl3/K2S2O8/Et3SiH system‐mediated α‐methylation of β‐ketosulfones with N,N‐dimethylformamide (DMF) was developed. In the overall process, DMF takes up the role of one methyl group in the generation of α‐methyl β‐ketosulfones via single carbon‐carbon (C‐C) bond formation under the reflux condition. Herein, a plausible reaction mechanism is proposed.