The present invention relates to a positive electrode active material for a secondary battery, a method for preparing the same, and a secondary battery including the same, and more particularly to a positive electrode active material for a secondary battery, which includes lithium transition metal oxide particles represented by Formula 1; and lithium metal phosphate nanoparticles disposed on the surface of the lithium transition metal oxide particles and represented by Formula 2, a method for preparing the same, and a lithium secondary battery including the same. Li(1+a)(Ni1-b-cMbCoc)O2  [Formula 1] In which, M is at least one metal selected from the group consisting of Mn, Al, Cu, Fe, Mg, Cr, Sr, V, Sc and Y, 0≦a≦0.2, 0≦b≦1, and 0≦c≦1. Li1+xM′xM″2-x(PO4)3  [Formula 2] In which, M′ is Al, Y, Cr, or Ca, M″ is Ge, Ti, Sn, Hf, Zn, or Zr, and 0≦x≦0.5.