Raney nickel is extensively used as a catalyst in the hydrogenation of vegetable oils. However, it deactivates over time and is known as a spent nickel catalyst, which is potentially hazardous to the environment. By contrasting different approaches, a straightforward and original strategy for regenerating spent nickel catalyst was developed by comparing various methods. The fresh, spent nickel catalyst, and treated catalyst samples were characterized using X-ray diffraction, Fourier transform infrared, atomic absorption spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, and color scheme analyses. The results showed that the catalyst deactivation was primarily due to oil deposition over the active sites, agglomeration of catalyst, and entrainment of nickel during hydrogenation. Using n-hexane as the solvent with a spent nickel catalyst-to-solvent ratio of 1:12 (g/mL), a 65 °C temperature, and a two-hour extraction time, ultrasonication-assisted solvent extraction of spent nickel catalyst proved to be the most effective and efficient process for regeneration.