ABSTRACT This study developed polypropylene (PP) nanocomposites containing surface-functionalized boron nitride (BN) decorated with BaTiO3 (BT). The developed nanocomposites showed well-dispersed nanoparticles in the PP matrix. The nanocomposites showed optimal hardness, elastic modulus, and stiffness of about 166.6 MPa, 2.7 GPa, and 0.12 mN/nm for PP/15BN-5BT nanocomposite compared to 79.4 MPa, 1.7 GPa, and 0.089 mN/nm measured for the pure PP, which are increments of about 110%, 59%, and 35% respectively. Heat deflection temperature and dynamic mechanical properties were also enhanced. Therefore, this study discussed the effects of BN decorated with BT on the nanomechanical and thermomechanical properties of PP nanocomposites.