As a class of persistent organic pollutants (POPs), polychlorinated biphenyls (PCBs) are highly hazardous to the ecosystem, and their effective and facile detection is of high importance. Herein, we present two nanoporous metal–organic frameworks (MOFs), (Me2NH2)­[In­(CPTTA)]·(DMF)1.5(H2O)3.5 (BUT-174) and (Et2NH2)­[In­(CPTTA)]·(DEF)­(H2O)3 (BUT-175), constructed by In3+ ions and the aromatic-rich tetratopic carboxylate ligands, 5′-(4-carboxylatophenyl)-[1,1′:3′,1″-terphenyl]-3,4′′,5-tricarboxylate (CPTTA4–), which exhibit highly efficient turn-down fluorescence response toward 12 PCBs, especially for three highly toxic non-ortho-substituted PCBs (PCB-77, -126, and -169) with the so-called “coplanar” molecular configuration in various solvents with the limits of detection (LODs) down to the ppb level owing to the inner filter effect between MOFs and PCBs. In addition, the MOFs show high sensing selectivity toward PCBs over many relevant interferents, including hexabromocyclododecane (HBCD), decabromodiphenyl oxide (DBDPO), perfluorobutanoic acid (PFBA), and perfluorooctanoic acid (PFOA), as well as good recyclability and stability. It is demonstrated by this work that structurally well-defined MOFs could be promising sensory materials for the detection of highly toxic PCBs in a facile way.