A Rh-catalyzed intermolecular coupling of diazomalonates with arene C H bonds is reported. The reaction is initiated by electrophilic C H activation, which is followed by coupling of the arylrhodium(III) complex with the diazomalonate. In most cases, arenes with oximes, carboxylic acids, and amines as directing groups cross couple with diazomalonates with excellent regioselectivities and functional group tolerance, and thus, this reaction offers a new route to alpha-aryl carbonyl compounds for specific applications.