The study focuses on the development of an efficient and sustainable solution for synthetic dye degradation through the hydrothermal synthesis of BiOCl and BiOCl/MXene heterostructures. Structural and compositional properties were analyzed by using X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM), and X-ray photoelectron spectroscopy (XPS) techniques. A significant reduction in the band gap of BiOCl/MXene to 2.97 eV from 3.62 eV for BiOCl was observed via UV spectroscopy, leading to enhanced photocatalysis with 89% degradation efficiency in just 12 min. The mechanism involved and reactive species were confirmed by LC-HRMS and radical trapping tests, while ICP-MS verified metal content in water before and after degradation. Additionally, the nanocomposite demonstrated a specific capacitance of 431.24 F g −1 at a current density of 1 mA cm −2 , with an excellent capacitance retention of 94.35% after 2000 cycles. This study highlights BiOCl/MXene as a promising material for both photodegradation and supercapacitor applications.