<p>The worldwide demand for lithium-ion batteries (LIBs) is rapidly increasing as electric vehicles powered by LIBs start to supplant traditional gasoline-powered automobiles. As part of the circular economy, used LIBs are becoming secondary sources of valuable metals. Valuable metals found in LIBs include lithium, nickel, cobalt, rare earth metals, and electrolyte chemicals. The LIBs used in EVs have a fixed durability, and the disposal of exhausted batteries poses a significant threat to our ecosystem. The improper disposal of used batteries releases harmful substances, such as heavy metals and electrolytes, due to environmental weathering. As a result, the appropriate disposal of LIBs while recovering valuable metals can provide resource recycling with a lower ecological risk. Considering these factors, the bio-hydrometallurgical routes provide a sustainable approach for recovering valuable metals to be reused in new batteries. For the extraction of valuable metals from spent LIBs, microbial technology provides an environmentally friendly method. Microorganisms like <i>Aspergillus niger, Penicillium, Leptospirillum ferrooxidans, Sulfolobus metallicus</i>, and <i>Acidithiobacillus thiooxidans</i> are used for the recovery of cobalt and lithium from spent LIBs. These strains catalyze the acidolysis and bio-oxidation processes that remove metals from LIBs. This review article provides an understanding of the bioleaching of LIBs as an eco-friendly and enhanced method for recovering valuable metals from spent LIBs.</p>