The metal–organic framework (MOF) of Cu3(btc)2 (btc = benzene-1,3,5-tricarboxylic acid) is covalently immobilized at chitosan (CS)–electrochemically reduced graphene oxide (ERGO) hybrid film modified electrode, which is characterized by scanning electron microscope (SEM), energy-dispersive X-ray spectra (EDS), and electrochemistry. The MOF-based electrode is applied as an electrochemical sensing platform for the simultaneous detection of dihydroxybenzene isomers (DBIs) of catechol (CT), resorcinol (RS), and hydroquinone (HQ). The results show that the DBIs present well-resolved and intense voltammetric signals at the modified electrode, due to the synergic effect contributing from Cu3(btc)2 with unique porous framework structure and ERGO with high electronic conductivity. The excellent distinguishing efficiency of the sensor toward DBIs is also confirmed by the quantum chemical computation. Quantitative analysis assays by differential pulse voltammetry shows that the sensor has wide linear ranges and low detection limits for the DBIs. The developed sensor is also applied for the determination of DBIs in the real water sample, and satisfactory results are obtained. This work strongly implies that the MOFs have great potential in the construction of novel electrochemical sensor for isomers.