Provided is a cathode active material including a complex coating layer, which includes M below, formed on a surface of the cathode active material through reaction of a lithium transition metal oxide represented by Formula 1 below with a coating precursor: LixMO2  (1) wherein M is represented by MnaM′1-b, M′ is at least one selected from the group consisting of Al, Mg, Ni, Co, Cr, V, Fe, Cu, Zn, Ti and B, 0.95≤x≤1.5, and 0.5≤a≤1. The lithium secondary battery including the cathode active material exhibits improved lifespan and rate characteristics due to superior stability.