<p>A novel strategy is presented for constructing ratiometric fluorescent detection platform based on terbium(Ⅲ) ion as a single luminescence center, enabling sensing of permanganate ions (MnO₄^‒) in water. The approach leverages the differential quenching mechanisms of MnO₄^‒ on distinct emission bands of terbium-based metal-organic frameworks (Tb-MOFs), using the intensity ratio of specific emission wavelengths (I₅₄₈/I₆₂₂) as the detection signal for MnO₄^‒ quantification. A ratiometric probe [Tb(BCB)(DMF)]<b>·</b>(DMF)_1.5(H₂O)₂ (H₃BCB: 4,4’,4’’-benzenetricarbonyltribenzoic acid) (<b>1</b>) was developed, demonstrating high selectivity, sensitivity, and anti-interference capability toward MnO₄^‒. The study of quenching mechanism reveals that the 622&#xa0;nm emission is quenched solely by the inner filter effect (IFE), whereas the 548&#xa0;nm emission undergoes synergistic quenching by IFE and Förster resonance energy transfer (FRET). This differential quenching leads to a distinct decrease in I₅₄₈/I₆₂₂, forming a robust ratiometric sensing platform. Notably, the method eliminates interference from dichromate ions (Cr₂O₇^2‒). The strategy’s generality is validated by a second Tb-MOF ([Tb(cpia)(H₂O)₂]_n·nH₂O (H₃cpia: 5-(4-carboxyphenoxy) isophthalic acid) (<b>2</b>)), which also functions as a ratiometric probe for MnO₄^‒. These findings establish a universal design principle for constructing single-luminescence-center ratiometric fluorescence platforms.</p> Graphical Abstract <p></p>