Arsenic contamination in drinking water poses a significant public health concern, necessitating effective treatment methods. While various technologies exist for arsenic removal, the presence of natural organic materials (NOM) can significantly impact treatment efficiency. This study investigated the removal of arsenic from organic-rich water using a novel iron-functionalized reduced graphene oxide (fRGO) nanocomposite. Fulvic Acid (FA) was selected as a representative organic matter to evaluate its influence on the arsenic removal process. The research examined multiple operational parameters, including pH, adsorption time, adsorbent dosage, and total organic carbon (TOC) concentration. Experimental results demonstrated that these parameters exhibited antagonistic effects on the removal efficiency of arsenic. Despite the advanced nature of the fRGO adsorbent, the maximum arsenic removal achieved was limited to 60% when organic matter was present, highlighting the significant impact of TOC on treatment effectiveness. To address these complex interactions, a comprehensive mathematical model was developed incorporating all four key parameters. This model serves as a valuable tool for predicting optimal conditions for arsenic removal and understanding the intricate relationships between operational parameters in the presence of organic matter. The findings provide crucial insights for improving arsenic removal strategies in organic-rich water systems.