The current study focuses on the effect of Acrylate-styrene-acrylonitrile (ASA)/Nanosilica (Si) modified binders on the complex modulus (G*) and rutting resistance parameters (G*/ sinδ) of Asphalt Cement (AC). Four different blends including the base binder and the polymer nanocomposites which were formed by blending 5% ASA to base binder with the addition of nanosilica at 3, 5 and 7% by the weight were the subject of investigations. Conventional and Dynamic Shear Rheometer (DSR) testing procedures were conducted as well as morphology analysis using Fourier Transform Infrared Spectroscopy (FT-IR). The rheological characteristics of AC were analysed by master curves, isochronal plots and rutting resistance parameter plots. Test results revealed that G* and G*/ sinδ of all modified samples were significantly enhanced compared to the base binder. Multiple Stress Creep Recovery Test (MSCRT) conducted at 100 Pa and 3200 Pa showed that, non-recoverable compliance was reduced and elastic recovery of modified binders were improved. Optimum concentration was found to be 5% ASA/Si composite, as further addition of polymer nanocomposite resulted in lower enhancement in the rheological properties of modified AC due to the occurrence of agglomeration between the composite and the base binder.