A 3D heterometal–organic framework {[TbZn(BPDC)2(HCOO)(H2O)3]·2H2O}n (1) was constructed from Tb3+ and Zn2+ as metal ions and 4,4′-dicarboxylate-2,2′-dipyridine (H2BPDC) as the ligand using a solvothermal method. Single-crystal X-ray diffraction analysis revealed that compound 1 is 2-fold interpenetrating. Thermogravimetric and solvent stability analyses demonstrated that compound 1 displayed good thermal and solvent stabilities. The luminescent explorations revealed that compound 1 exhibited highly sensitive and qualitative detection of nitrobenzene at the ppm level. To our knowledge, the present study reports for the first time the use of an interpenetrating heterometallic metal–organic framework as a luminescent probe for nitrobenzene.