The aim of this study is to evaluate the effectiveness of chemically and biodegradable agricultural waste sorbents and their synthesized bio-nanoadsorbents based on nanoparticles in the remediation of water environments contaminated by oil spills. A new bio-nanocomposite was developed by combining pomegranate peel and Fe3O4 magnetic nanoparticles. Based on the adsorption results, it was determined that the adsorption efficiency of 10% pomegranate peel/Fe₃O₄ bio-nanoadsorbent (pH = 7, 0.5 g adsorbent, 78 g/L oil) was 82%, while the adsorption efficiency of the biosorbent obtained with pomegranate peel alone was 52%. The Brunauer–Emmet–Teller (BET) surface area of the synthesized dried bio-nanoadsorbents ranged from 67 m²/g. The results of regeneration experiments showed that the bio-nanoadsorbent could be reused up to 96%. Based on desorption experiments, it was determined that the pomegranate peel/Fe3O4 bio-nanoadsorbent desorbed 63.28% of oil with ethanol and 71.9% with acetone. According to the experimental results, it can be argued that the pomegranate peel/Fe3O4 bionanocomposite is a new effective adsorbent for the removal of oil and oil products from aqueous solutions and therefore has the potential to be used in environmental pollution cleanup programs.