Natural ecological processes and ecosystems have been significantly impacted by the production of liquid and solid hazardous wastes. Different types of waste are generated including agrochemical, animal, industrial, domestic, medical, municipal, and sewage sludge from a variety of anthropogenic activities. Traditionally, the most popular methods for handling solid trash were landfilling and burning, while liquid waste was used to release into various water bodies. These methods of waste disposal led to issues with bad odour, water contamination, health issues, and air and water pollution. The development of alternative waste treatment procedures has become necessary due to the introduction of increasingly strict rules for the discharge of waste into the environment. Enzymes can be used as a sustainable alternative to traditional waste treatment practices. The involvement of enzymes in waste treatment processes would be a widely applicable approach due to the specific nature of enzyme-catalysed reactions. Hazardous wastes can be directly or indirectly processed by enzymes through chemical and physical alterations. Additionally, enzymes can assist in transforming waste materials into valuable products or alter the properties of a specific waste to make it more susceptible to treatment. The main classes of enzymes used to transform hazardous wastes into non-toxic or biodegradable compounds include hydrolases, lipases, oxidoreductases, oxygenases, and laccases. The present book chapter summarises an overview of research carried out to develop enzymatic treatment processes for the management of hazardous liquid and solid waste materials.