In the current study, the bleaching technique with sodium hypochlorite (NaOCl) was used to modify black tea waste (BTW) for enhancing its biosorption performance of Methylene blue (MB) dye. Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), (thermogravimetric-differential thermal analysis) TG/DTA, X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) analysis and surface acidity and pH_pzc measurements were employed to determine the textural structure and surface chemistry of the raw and NaOCl-modified BTW. The results indicate that after using bleaching modification, the MB biosorption capacity of BTW was enhanced approximately threefold. Maximum biosorption capacities were found as 125 mg g⁻¹ for BTW and 416.67 mg g⁻¹ for bleached black tea waste (BBTW).