L11-type (Co–Ni)–Pt ordered alloy perpendicular films were successfully fabricated on MgO(111) single crystal substrates using ultrahigh vacuum sputter film deposition; the addition of Ni to Co–Pt was effective to reduce saturation magnetization, Ms, maintaining a large Ku of the order of 107 erg/cm3. L11-type ordered structures, with the <111> direction (easy axis of magnetization) perpendicular to the films, were successfully fabricated at a substrate temperature of 360 °C in a wide composition range with Co content less than 60 at. %. The order parameter, S, was almost a constant of about 0.5 in the stoichiometric composition of (Co1-XNiX)50Pt50, independent of Ni content, X. L11-type Co–Ni–Pt perpendicular films having a large Ku of (1–2.5)×107 erg/cm3 and a relatively low Ms of 400–700 emu/cm3 were successfully fabricated in the composition range of 10–35 at. % Co, 20–55 at. % Ni, and bal. Pt. Ku should increase further with enhanced ordering. Experimental results demonstrated the potential of these Co–Ni–Pt ordered films for use in data st- orage applications due to very high Ku potential comparable to L10-type Fe50Pt50 films, relatively low Ms, the relatively low fabrication temperature, and good controllability of the grain orientation.