Herein, an eco-friendly carboxymethyl cellulose (CMC)/metal-organic framework (MIL-101(Fe))/ copper oxide (CuO) biocomposite (CMC/MIL/CuO) was synthesized as a photocatalyst and characterized and its ability to decolorize Acid Blue 92 dye was investigated. The synthesized biocomposite was identified by FTIR, BET, XRD, DRS, SEM, EDS and MAP analyzes. The efficiency of the novel eco-friendly biocomposite photocatalyst was studied by performing a series of experiments under optimized parameters such as catalyst dose, pollutant concentration, and time. The data presented that the dye degradation kinetics follows the zero-order kinetic model with high correlation coefficient. The efficiency of photocatalytic decolorization using 0, 1, 2, 3, and 4 mg of CMC/MIL/CuO are as follow: 8.5, 58, 83, 100, and 100 %, respectively. The degradation rate constant of CMC/MIL/CuO for 20, 30, 40, and 5 mg/L AB92 was 0.1517, 0.1884, 0.194, and 0.2045 mg/L min (zero-order rate), 0.023, 0.011, 0.007, and 0.006 min 1 (first-order rate), and 0.0140, 0.0012, 0.0006, and 0.0004 L/mg min (second-order rate), respectively. Decolorization increases by catalyst dose and decreases by contaminant concentration. The photocatalyst regeneration was carried out for 5 cycles, which for all 5 cycles the decolorization efficiency remained above 95%. The results showed that the CMC/MIL/CuO novel biocomposite can be used as a suitable photocatalyst for the dye decolorization.