The present invention relates to a cosmetic composition for oxidation dyeing keratin fibers comprising, in an aqueous medium: (1) at least one oxidation dye; (2) at least one oxidizing agent; and (3) 1.5 wt % or more, relative to the total weight of the composition, of at least one amphoteric surfactant which is preferably a betaine-type amphoteric surfactant that may preferably be selected from the group consisting of alkylbetaines, sulfobetaines, alkylamidoalkylbetaines and alkylamidoalkylsulfobetaines, in particular alkylbetaines. The present invention is useful because the cosmetic composition according to the present invention can be prepared by a simple and inexpensive process, avoiding potential compatibility issues, and can provide better cosmetic properties and color intensity.