The present invention relates to a positive electrode active material for a lithium secondary battery, a method for preparing the same and a lithium secondary battery including the same, the positive electrode active material includes a core including a first lithium complex metal oxide, and a shell located surrounding the core and including a second lithium complex metal oxide, and further includes a buffer layer located between the core and the shell, wherein the buffer layer includes a pore, and a three-dimensional network structure of a third lithium complex metal oxide which is connecting the core and the shell, and accordingly, minimizing destruction of the active material caused by a rolling process during the electrode preparation, and maximizing reactivity with an electrolyte liquid.