Because of their superior optical, luminescent, catalytic, magnetic, and electrical characteristics, nanomaterials have shown great promise in the realm of sensing. The potential to establish better control over the analytical performance of formed sensors is due to the simplicity of manufacturing and adjustable characteristics of a broad variety of nanomaterials. Herein, a comprehensive review on carbon-based quantum dots, noble metals (Au, Ag, Pt), and other metal, metal oxide and sulphides based nanoparticles including ZnO, CeO2, TiO2, SnO2, ZrO2, CdS, CdSe, CuS, CuO, ZnS, WO3, Cr2O3, Gd2O3, Yb2O3-based electrochemical, optical, fluorescence, and pH-dependent sensors for detecting harmful metal ions (Hg2+, Pb2+, Cd2+), and so on are discussed. This review also discusses the utilization of different nanomaterials to fabricate enzymatic and non-enzymatic electrochemical sensors. Sensors to detect agrochemical contaminants and other hazardous materials are also discussed. Finally, the future perspectives and current challenges in achieving large-scale commercialized nanomaterials-based sensors are reviewed.