Highly efficient and environmentally friendly carboxylated cellulose silica hybrid adsorbents were prepared by combining the advantages of cellulose and silica. The surface property and chemical composition of produced cellulose silica hybrid adsorbents were extensively characterized via different techniques. The results indicated that silica particles were densely deposited on the surface of composite adsorbents. Because of their porous structure and large specific surface area, the carboxylated cellulose silica hybrid adsorbents demonstrated a high capacity of methylene blue (MB) adsorption, exceeding 990 mg·g-1. This adsorption capacity was more than 45% higher than that of carboxylated cellulose adsorbent. The cellulose silica hybrid adsorbents were able to maintain an MB adsorption efficiency of up to 70% even after undergoing five cycles. This study developed cellulose silica hybrid adsorbents for wastewater treatments. High adsorption capacity and stability make them sustainable and cost-effective alternatives to traditional adsorbents.