A promising and economic aerogel for dealing with environmental problems, such as dye pollution or oil spillage, is successfully produced from coconut fibers (CFs), the by-product of the coconut industry. Coconut fibers (CFs) are converted into bio-based aerogels via the alkali-urea method and cost-effective freeze-drying. This environmental-friendly recycled aerogel, successfully fabricated by green solvents alongside recovering used chemicals and by-products, has an ultra-low density (0.038–0.067 g/cm³), a high porosity (94.2–96.7%), and Young’s modulus of up to 176.6 kPa. In addition, the as-fabricated aerogels exhibit a high adsorption capacity of up to 46.9 mg/g for crystal violet (CV) with an initial concentration of 200 ppm. The equilibrium state of CV adsorption by CF aerogels is achieved after 30 min with the highest dye removal of 94.6% at the initial concentration of 50 ppm. Besides, its hydrophobic properties and its maximum oil adsorption capacity (approximately 19.3 g/g) are measured after coating aerogel samples with methyltrimethoxysilane (MTMS). Moreover, the CF aerogel and modified CF aerogel exhibit good reusability of 3 and 4 times with the adsorption capacity of 10.9 mg/g and 8.7 g/g, respectively. CF aerogels are proved as an eco-friendly adsorbent having great potential for wastewater treatment because of their significant sorption of oil and dyes.