The preparation, characterization, and adsorption characteristics of lignin/silica nanocomposites are described. The nanocomposites were obtained from cellulosic ethanol residue (CER) by an in situ method. The lignin was used as a structure directing reagent, and sulfuric acid as precipitating reagent during the synthesis of lignin/silica nanocomposites. The effects of pH on the properties of the nanocomposites have been investigated in detail. The prepared nanocomposites were characterized by the FT-IR, SEM, TG-TGA, XPS and low-temperature nitrogen sorption methods. Adsorption capacities and adsorption behaviors of selected lignin/silica nanocomposite, lignin, and silica for Methylene Blue (MB) were also studied, respectively. The results indicated that the lignin/silica nanocomposite is a good candidate for a biosorbent, providing a potential route for the high value-added utilization of CER.