<p>This study presents a novel approach to enhancing the performance of ethylene-propylene-diene monomer (EPDM) and acrylonitrile-butadiene rubber (NBR) composites by reinforcing them with graphene oxide (GO) modified using 4,4-diphenylmethane diisocyanate (MDI). While GO has been widely used as a nanofiller in rubber matrices, the use of MDI-functionalized GO (MDI-GO) in EPDM/NBR blends has not been previously reported. The modified nanofiller was incorporated using an open-mill mixer, and its effect on composite morphology was examined via field emission scanning electron microscopy. The study systematically evaluated the cure characteristics, mechanical properties, compression set, abrasion resistance, and swelling resistance of the composites. Results showed that EPDM/NBR/MDI-GO composites outperformed both unfilled and GO-filled composites. Notably, the MDI-GO-reinforced composite achieved a 137% increase in tensile strength, 59% in stress at 100% elongation, and 101% in tear strength compared to the base compound. Abrasion resistance also improved with increasing MDI-GO content, attributed to enhanced interfacial interaction and filler dispersion. These findings demonstrate the effectiveness of MDI surface functionalization in significantly improving rubber nanocomposite performance.</p> Graphical abstract <p></p>