As batteries are widely used, LiFePO disposal is booming4th (LFP) batteries are coming. Both pyrometallurgical repair and hydrometallurgical processes have been used in recycling used LFP batteries. The former is only of limited use due to its poor adaptability to used LIBs with different chemical properties or inconsistent degrees of damage, while the latter achieves poor economic returns due to the low added value of its products iron (III) phosphate and lithium carbonate. In this study a simple process for the direct regeneration of LiFePO4th from spent LFP cathode material that includes acid leaching and hydrothermal synthesis is suggested. The results show that the acid leaching process of the spent LFP cathode material is dependent on the surface chemical reaction and that 96.67% lithium and 93.25% iron leaching efficiency can be achieved simultaneously by controlling the thermodynamic conditions. In addition, component control and a one-step hydrothermal process were used to successfully regenerate a flake-like LFP cathode material directly from the leach solution. The regenerated LFP cathode material shows good electrochemical performance and its discharge capacity is 136 mAhg−1 at 0.1 ° C. After 300 cycles at 1 ° C, its capacity retention ratio is 98.6%. In addition, an economic evaluation shows that the process is profitable. Therefore, the approach proposed in this study could help avoid the complex element separation process and achieve easy recycling of LFP cathode material, providing a novel and efficient method for the clean and economical recycling of used LFP cathodes.