The creation of nickel-smelting products including important metals like nickel, cobalt, and copper is a persistent issue in the nickel mining business. Another secondary source of precious metals is nickel slag. In addition, the massive amounts of nickel slag generated by the nickel smelter sector will pollute the environment, particularly the soil, since the smelting slag contains hazardous materials. This study examines techniques for recovering precious metals from nickel slag by reviewing publications from Springer Link, Google Scholar, MDPI, ScienceDirect, Membrane Journal, and other authors. The two types of metal recovery techniques from nickel slag that were examined were hydrometallurgical and pyrometallurgical techniques. This review article describes a pyrometallurgical method that involves roasting and selective reduction. In the meantime, the hydrometallurgical techniques were examined in the high-pressure oxidative acid leaching process, the atmospheric acid leaching method, and the bioleaching process. A roadmap for research designs that can be used to recover valuable metals from nickel slag sustainably has been created due to the completed literature evaluation.