The present invention relates to a method for fabricating a LiFePO4 cathode electroactive material for a lithium secondary battery by recycling, and a LiFePO4 cathode electroactive material for a lithium secondary battery, a LiFePO4 cathode, and a lithium secondary battery fabricated thereby. The present invention is characterized in that a cathode scrap is heat treated in air for a cathode electroactive material to be easily dissolved in an acidic solution, and amorphous FePO4 obtained as precipitate is heat treated in an atmosphere of air or hydrogen so as to fabricate crystalline FePO4 or Fe2P2O7. According to the present invention, a cathode scrap may be recycled by using a simple, environmentally friendly, and economical method. Further, a lithium secondary battery fabricated by using a LiFePO4 cathode electroactive material from the cathode scrap is not limited in terms of performance.