NO2− sensing is closely associated with human health, and we adopted lanthanide Eu3+ post‐modified MOF as NO2− fluorescent probes. Typical stable MOF with uncoordinated carboxylic groups in the framework were chosen to encapsulate Eu3+. NO2− could generate an obvious quenching response to the fluorescence intensity. This Eu3+ functionalized MOF exhibited excellent fluorescence performances and obvious quenching response to NO2− based on the energy transfer between Eu3+ and NO2−. This MOF based NO2− fluorescent probe showed a highly splendid detection selectivity and sensitivity with a very low detection limit of 0.69 μM, which was significantly below the maximal level limits of NO2− in drinking water set by the WHO.