Abstract We herein describe an efficient iron‐catalyzed selective N ‐methylation and N ‐formylation of amines with CO 2 and silane using mono‐phosphine as ligand. With commercially available [CpFe(CO) 2 ] 2 as catalyst, Fe‐catalyzed methylation of amines was achieved with triphenylphosphine as a ligand. Using tributylphosphine as a ligand, Fe‐catalyzed formylation of amines was realized at a lower temperature. The method was successfully applied in the late‐stage methylation and formylation of drug molecules containing amine moiety. magnified image