It is no secret that the overexploitation of natural resources such as mineral ores is an unsustainable practice. Not only are these resources finite, but their extraction is often associated with severe environmental consequences during both the extraction and refining processes. Moreover, when a given country is entirely dependent on mineral imports, it is also susceptible to market constraints and geopolitical pressures. Because of this, mineral recycling from secondary sources and their injection back into the economy can prove to be an effective measure to mitigate the problems associated with primary mining. An example of such an approach is the recovery of valuable metals from spent lithium-ion batteries (LIBs). These batteries contain valuable metals such as lithium (Li), manganese (Mn), cobalt (Co), and nickel (Ni), as well as copper (Cu) and iron (Fe). Hydrometallurgical techniques such as solvent extraction have already been used with varying degrees of success to recover these metals from lithium-ion batteries. However, the existing processes can and should be optimized in terms of the extreme acidic conditions and hazardous chemicals that are used. In this work, we propose the use of novel deep eutectic solvents (DES) as alternative solvents in LIB recycling, using less acidic environments at room temperature. Trioctylphosphine oxide (TOPO)-based eutectic solvents were tailored to extract equimolar concentrations of different metals often present in LIBs leachates without the addition of heat and even displayed selective extraction for some metals under specific conditions. Further characterization, including acid partition into the DES, viscosity, and reusability, allowed for a more rigorous assessment of potential applications. Overall, TOPO-based DES exhibited promising behavior in terms of metal extraction from LIB leachates.