The exponential growth of the Li-ion battery (LIB) market necessitates the development of environmentally friendly and economically viable recycling technologies. One of the approaches for recycling and selective recovery of critical battery components is the hydrometallurgical method. Despite its effectiveness, this technology has notable drawbacks, including environmental pollution caused by corrosive waste, high energy consumption, and complexity. Herein we present a highly efficient mechanochemically (MC) induced acid leaching process that enables the extraction of transition metals as water-soluble salts from cathode materials of different and mainly used chemistries such as LiCoO₂, LiMn₂O₄, and Li(CoNiMn)O₂. The described method utilizes HNO₃, H₂SO₄, and HCl mineral acids to leach transition metal composites obtained by MC reduction and delithiation processes. The presented technology achieves a significant material dissolution efficiency of more than 95 % at low acid concentrations at room temperature. Furthermore, it was concluded that the mechanochemical pretreatment step plays a crucial role in reducing particle sizes as well as for the chemical reduction of d-elements in the cathode materials to lower electrochemical charging states which greatly enhances the effectiveness of the leaching process. This advancement brings us closer to achieving ecological and economic feasibility in recycling Li-ion batteries.