<p>In this study, ethylene-propylene-diene monomer/acrylonitrile-butadiene rubber (EPDM/NBR) nanocomposites were developed by incorporating a hybrid filler composed of polyhedral oligomeric silsesquioxane (POSS) and multiwalled carbon nanotubes (MWCNT) using a two-roll mill mixing technique. The research focused on evaluating cure characteristics, mechanical properties, abrasion resistance, compression set, swelling resistance, and crosslinking density of the prepared nanocomposites. The findings revealed that increasing the hybrid filler content led to a decrease in minimum torque, maximum torque, delta torque, and cure rate index, while scorch time and optimum cure time increased. Tensile strength and stress at 100% elongation improved with filler addition up to 4 phr but declined at higher concentrations. Hardness and tear strength generally increased with filler content, whereas elongation at break and rebound resilience showed a decreasing trend. Compression set values increased as filler content rose. Swelling resistance and abrasion resistance initially improved with the incorporation of 4 phr of hybrid filler but diminished at higher concentrations.</p>