Two novel 2D lanthanide metal-organic frameworks (Ln-MOFs), namely {[Eu2(DBTA)3(DMF)2]·DMF}n (1) and {[Tb2(DBTA)3(DMF)2]·DMF}n (2) (H2DBTA = 2,5-dibromoterephthalic acid), have been successfully synthesized by the solvothermal method. Single-crystal X-ray diffraction results proved that the complexes possess the same topological structure of a (42·6)2(42·84)(47·63)2-connected net. The recognition of CN- from interfering anions with a low detection limit by "turn-off" luminescence makes them promising candidates for the highly selective and sensitive detection of the cyanide ion. The Ln-MOFs 1 and 2 exhibit excellent chemical sensing properties for CN- with efficiency, selectivity, and excellent performance in various mixed anions. The evaluation parameters, including the quenching constant and detection limit, have been investigated to obtain the detection performance for CN-.