The emerging and legacy contaminants are toxic chemicals and they are polluting and degrading the environment with huge loss of life and economic growth. There are several emerging contaminants that are posing severe health issues for both humans and animals. The per- and polyfluoroalkyl substances (PFASs), polybrominated diphenyl ethers (PBDEs), phthalates, and short-chain chlorinated paraffin (SCCPs) are considered as most toxic emerging contaminants (ECs). ECs are pharmaceuticals and personal care products, endocrine-disrupting compounds, a few pesticides, veterinary products, disinfection by-products, and fire-retardant chemicals. The legacy contaminants such as pesticides, lead, mercury, arsenic, dioxin, dioxin-like compounds, and chlorinated naphthalenes are polluting the environment with higher health issues in humans and wild animals. The emerging and legacy contaminants are spreading through air, water, and soil. In animals and humans, contaminants are reaching their bodies through bioaccumulation and bio-magnification process. Globally, millions of people are affected by serious health issues including cancer in various organs, malfunction of sensitive organs, neural disorders, reproductive impairments, hormonal disorders, immune failure, stress, diabetes, and various traumas, and numerous individuals have been died due to overuse of toxic chemicals. Similarly, intensive physiological and behavioral disorders and diseases have been documented in animals due to the unlimited use of emerging and legacy chemicals. Standard operating procedures, rigid guidelines, monitoring protocols, and management of toxic chemicals should be strengthened to minimize the various health issues and loss of biodiversity due to the use of toxic chemicals.