The development of applications of ionic liquids in extraction processes stretches back to the mid-1960s when the first studies on ionic liquid-based extractions were published. Since then, the interest of both academics and the industrial community on the development of ionic liquids-based technologies is continuously growing. The main driving force of ionic liquid engineering is to combine their "environmentally friendly" properties (e. g., extremely low vapor pressure) and their unique reactivity and miscibility behavior in order to improve the current "state of the art" technologies. The focus of this review is on the application of ionic liquid in heavy metal extraction processes. The critical aspects of their journey from academic curiosity towards industrial application are highlighted.