Understanding the ion transport mechanism in nanocomposite solid polymer electrolytes is necessary to develop next-generation electrochemical devices. We investigate the role of inorganic nanoparticle on ion conduction and segmental dynamics in cross-linked epoxy-based nanocomposite solid polymer electrolytes, complexed with Li+F3CSO2NSO2CF3- (LiTFSI) salt and Al2O3 nanowire, using dielectric relaxation spectroscopy. The addition of Al2O3 not only increases the ionic conductivity crpc by up to similar to 10 times but also accelerates the segmental a motion compared to the host electrolyte. Increasing Al2O3 content leads to a reduction in segmental a relaxation temperature T-alpha (fast dynamics), resulting in increased ion mobility as well as an enhancement in segmental a relaxation strength Delta epsilon(alpha) lowering ion dissociation energy, as revealed by density functional theory calculations, thereby providing more mobile ions for conduction. This ion transport investigation provides insights into the design of high-conductivity nanocomposite solid polymer electrolytes for energy applications.