<p>Water pollution from dyes, pesticides, and antibiotics poses a significant threat to living organisms, including humans and animals. There is an urgent need to develop efficient materials that are capable of degrading various organic pollutants. The main focus of this investigation was to synthesize iron oxide nanoparticles (Fe₃O₄ NPs) by utilizing the litchi fruit shell extract and assessing their photocatalytic potential in the degradation of malachite green dye and an oxaprozin antibiotic. Furthermore, the antibacterial potency of the material was tested against <i>Streptococcus pyogenes</i> (<i>S. pyogenes</i>), <i>Staphylococcus aureus</i> (<i>S.aureus</i>), and <i>Escherichia coli</i> (<i>E.coli</i>) bacteria. The FTIR spectrum of the material exhibits distinct peaks 514 and 584 cm⁻¹, which are associated with Fe-O stretching vibrations of the material. SEM analysis reveals that the average particle diameter was 45 nm. The material shows potent photocatalytic activity against malachite green dye, and oxaprozin 82% dye and 34% antibiotics being removed from the water sample under the conditions used. The material shows maximum antibacterial efficiency against the Staphylococcus aureus with a 19 mm zone of inhibition. The innovation of this approach lies in the use of the litchi fruit shell extract as a natural reducing and stabilizing agent, which enhances the stability and properties of the Fe₃O₄ nanoparticles. This plant-based strategy for developing Fe₃O₄ NPs directly contributes to the Sustainable Development Goals and circular economy principles.</p> Graphical Abstract <p></p>