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.