The industrial revolution and technological advancements have introduced a myriad of chemicals into the environment, leading to extensive pollution and threats to living organisms. Persistent organic compounds (POPs), such as organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs), continue to pose environmental challenges even after their discontinuation. Furthermore, both legacy and emerging contaminants (ECs), such as pesticides, pharmaceuticals, industrial chemicals, and personal care products, have raised public concern due to their persistence, potential for bioaccumulation, toxicity, and ability to be transported over long distances. Nanoparticles and treatment by-products further complicate the issue, requiring advanced detection methods. The scientific community has already identified occurrences of the legacy and emerging contaminants in different environmental compartments, including aquatic systems, indicating a ubiquitous occurrence of the legacy and emerging pollutants in the environment. This pollution demands effective management, as the pollutants are liable for serious health concerns for human, animal, and other biotic components. Effective management strategies for these contaminants involve identifying contaminants, characterizing their sources and pathways, evaluating threats, establishing standards, and developing monitoring techniques, including biosensors, etc. Legislative frameworks and regulations are essential for addressing both existing and emerging contaminants, necessitating a comprehensive understanding of their environmental and health impacts. This chapter provides an overview of legacy and emerging contaminants as well as the regulatory and legislative instruments developed at different levels (i.e., national and international) to address the legacy and emerging contaminants-associated environmental challenges. Additionally, both mandatory and optional management strategies and actions are also outlined.