The present disclosure is directed to a negative electrode active material for lithium secondary batteries, to a method for preparing the same, and to a lithium secondary battery including the same, the negative electrode active material including a porous core in which scaly silicon fragments are connected in an entangled manner; and a shell layer covering the core, where the shell layer includes a carbon-based material and silicon, and the shell layer has a thickness in a range of more than 10 to less than 60% with respect to an average particle diameter D50 of the negative electrode active material.