The drinkable water scarcity has been increased worldwide due to the mixing of numerous hazardous organic and inorganic pollutants in water bodies, urging to find sustainable water remediation techniques. In this work, the naturally available HNT was modified with Ag nanoparticles through lignocellulosic waste material, i.e., Sonneratia Ovata leaf extract. A Sonneratia Ovata leaf derived Ag nanoparticle loaded halloysite nanotubes catalyst have developed with varying Ag nanoparticles loading over HNT surface, i.e., 0.25:1, 0.5:1, 0.75:1. Various characterization techniques were performed to confirm the formation of the Ag nanoparticles over HNTs surface. Then the prepared Ag loaded HNTs (Ag@HNT) were employed as photocatalysts for the removal of Methylene blue dye. It has been observed that, as compared to bare HNT, Ag@HNT based catalyst with ratio 0.5:1 exhibited efficient dye degradation. Around 95% of dye degraded within 30 min as confirmed by UV-vis spectrometer. Furthermore, to explore the kinetics and adsorption isotherm of the dye removal reaction under the presence of prepared catalysts, the models including pseudo first and pseudo second order, Elovich model, intraparticle diffusion, Langmuir model, Freundlich model, and Temkin model were detailed. The novelty of the present investigation lies in the development of a green synthesis method for silver nanoparticles using mangrove leaf ( Sonneratia-Ovata ) extract without any toxic reducing agent. Also, the naturally available HNT used as a substrate to support the formation of catalytically active silver nanoparticles. The prepared material produces high catalytic activity than previously reported results. © 2025 The Authors.