Different metal ions and anions are crucial for the life of organisms, but their excessive intake or deficiency cause various physiological abnormalities or diseases. Toxic metal ions such as Hg2+, Cr6+, Cd2+, explosive nitroaromatic compounds, and volatile organic compounds are widely used in agriculture, rocket fuels, and industry, but they cause severe effects on human health and environmental change. Hence, sensing and identification of these analytes are important for life, health, and environment protection. Recently, metal-organic frameworks (MOFs) have been extensively explored as luminescent sensors due to their unique crystallinity, structural diversity, tunable porosity, and functional groups. This chapter reviewed the origin of luminescent of MOFs and its applications as luminescent sensors for detecting different environmentally toxic analytes such as metal ions, anions, nitroexplosives, and volatile organic compounds. In addition, the detection mechanism of MOFs and its structural dependent properties are also illustrated.