Thermoplastic polyurethanes (TPUs) are among the most versatile engineering polymers. The presence of hard and soft segments on their backbone and specific hydrogen bond interactions between the hard segments provide TPUs with outstanding engineering properties. Nanofillers are incorporated in the TPU matrix in order to compensate for the mechanical property loss due to weakening of the hydrogen bonding between hard segments at higher temperatures and also to enhance other properties such as thermal and electrical conductivity, fatigue life, tribological properties. In this study, hybrid carbon nanofillers with different geometric shapes, namely rod like (1D) carbon nanotubes and sheet like (2D) graphene nanoplatelets were incorporated in the TPUs. TPU nanocomposites were prepared via a sustainable in-situ polymerization of Polycaprolactonediol, 1,4- Phenyldiisocyanate (PPDI) and Butanediol (BDO) in the presence of hybrid carbon nanofillers using a two step method. Mechanical and thermal properties of TPU nanocomposites with different ratios of carbon nanotube/graphene nanofillers were investigated. Differences in mechanical behavior were attributed to the formation of different types of 3D percolated networks when using hybrid nanofillers at different ratios.