<p>This research work investigates designing the ZnBi₂O₄/g-C₃N₄ p–n heterojunction for efficient and sustainable environmental remediations. The bare and nanocomposite was successfully synthesized through one pot hydrothermal followed thermal decomposition technique. As prepared materials were characterized by various analytical techniques to examine the phase structural, vibrational modes, texture morphology and light behaviours through powder X-ray Diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM-EDX), Ultraviolet-Visible Diffuse Reflectance Spectroscopy (UV-DRS). To investigate the photocatalytic activity of malachite green dye was utilized as artificial contaminants. The experimental outcomes revealed the established capacity of ZnBi₂O₄/g-C₃N₄ nanocomposites to light absorption wavelength (501 nm) and reduction of band gap (2.26 eV) facilitated a novel domain in organic pollutant removal which could be synergistic effect of the ZnBi₂O₄/g-C₃N₄ p–n heterojunction for augment the charge carrier separation and transportation. Moreover g-C₃N₄ enhance the life time of the photoinduced charge carriers decreased the recombination rate. ZnBi₂O₄/g-C₃N₄ p–n heterojunction nano composite achieved the highest degradation efficacy is 90 % compare to pristine materials ZnBi₂O₄ (77%), g-C₃N₄ (71%) of malachite green dye under visible light exposure in 100 min, with a pseudo-first-order rate constant of 0.02101 min⁻¹. Notably, the catalyst demonstrated excellent cyclic stability over five cycles. All the positive aspects of findings suggest that ZnBi₂O₄/g-C₃N₄ nanocomposites possess to serve as a capable and multifaceted material for the energy and environmental applications.</p>