The environment and biological ecosystems are currently facing significant destruction due to industrial organic pollutants and oil spills. In this study, an ultralight aerogel was synthesized from waste biomass modified with a renewable copolymer of waste cooking oil-co-stearyl methacrylate applicable for efficient oil-water separation. The hydrophobic aerogel was demonstrated through a combination of deep freezing, sol-gel processing, and solvent exchange deposition utilizing waste coir fiber blended with waste tissue paper. The aerogel possesses a porous architecture and remarkable characteristics such as low density (0.028 g/cc), high porosity (98.3%), and high oil sorption capacity (40.4 g/g). Additionally, the coir fiber aerogel displays exceptional hydrophobicity with a water contact angle of 130.8°, indicating its great potential for effectively separating oil-water emulsions.