A composite cathode active material, a method of preparing the composite cathode active material, and a lithium secondary battery including a cathode including the composite cathode active material are provided. The composite cathode active material includes: a nickel-based active material including about 60 mol % or more of nickel; and a coating layer on a surface of the nickel-based active material, the coating layer including a lanthanide composite. The composite cathode active material includes or is in the form of single crystal particles having an average particle diameter in a range of about 2 μm to about 8 μm.