To separate and recycle the Pt/C catalyst from the waste membrane electrode assembly (MEA) of proton exchange membrane fuel cells in an eco-friendly manner, used MEA was treated with ultrasound in a solution to separate the Pt/C catalyst and the proton exchange membrane after the gas diffusion layer (GDL) was removed. To eliminate the ionomer from the separated Pt/C, two methods were used: high-temperature heat treatment and environmentally friendly solvent treatment. MEA was remanufactured using the ionomer-free Pt/C catalyst, and fuel cell performance was evaluated. The residual content and removal rate after ionomer separation were examined using TGA and FT-IR analysis, revealing the potential for reuse of the catalyst in fuel cells through optimal ionomer separation.