The use of biopolymers and synthetic adsorbents for wastewater treatment is gaining more importance due to their ease of preparation and nontoxic nature. This study focuses on developing a new biopolymeric composite using Polyaniline and a leafy mulch of mango plants (PANI/ML) and applied to remove an anionic dye, i.e.: Direct Red-28 from water on a lab scale. Samples were characterized by various spectrochemical methods, like FT-IR, UV–Vis, and SEM analysis, and then used for adsorption studies. Results indicated that PANI/ML nanomaterial removed 203.25 ± 0.57 mg/g of Direct Red-28 dye, following chemisorption and pseudo-2nd order kinetic model with inter-layer diffusion mode. Desorption studies indicated that it can be recycled three times effectively. So, this composite can be used for adsorptive bioremediation of synthetic anionic pollutants.