The increasing presence of dyes in wastewater necessitates the development of efficient and sustainable remediation methods. This study investigates the potential of a novel bio-sorbent, chitosan-rice straw (CHRS) composite hydrogel particles, for the removal of methylene blue dye from aqueous solution. Systematic experiments were conducted by varying dye concentrations and bio-sorbent dosages and contact time. Furthermore, UV–Vis spectroscopy, scanning electron microscopy analysis, and FTIR test were employed for the analysis of removal efficiency of dye. The adsorption behavior of methylene blue dye on bio-sorbent followed Freundlich adsorption isotherm model (R2 = 0.894). Overall result analysis indicated that bio-sorbent synthesized using chitosan-rice straw composite hydrogel particles efficiently removed the methylene blue dye with efficiency of 92.81% after 24 h of contact time. The findings demonstrate the CHRS as an affordable, effective, and eco-friendly alternative to conventional adsorbents used in wastewater treatment methods.