The aim of this study is to investigate the effects of polyhedral oligomeric silsesquioxane (POSS) nanoparticle incorporation in silicone rubber (SR) on the reinforcing fiber-matrix adhesion as a function of POSS type. The nanocomposites of SR/POSS nanocomposites were prepared by using a laboratory type internal mixer at pre-optimized conditions. Three different POSS types having different functional groups, expected to give a grafting reaction with SR, were selected. As the reinforcing fiber, resorcinol-formaldehyde latex (RFL) treated aramide fibers were kindly provided by Kordsa Global Company. The mechanical, thermal and morphological properties of the matrix were evaluated. The mechanical adhesion between fiber and the matrix was determined by means of H-peel tests. The thermodynamic interaction between fibers and silicone rubber was determined from the surface free energy measurements in order to understand the adhesion mechanism. A correlation between thermodynamic adhesion and H-peel test was investigated. The effect of POSS type on the adhesion was discussed.