Electrically conductive thermoplastic polyurethane (TPU) composites with carbon nanostructures (CNS) (branched carbon nanotubes) and their hybrids with carbon nanotubes (CNT) or graphene nanoplatelets (GNP) were fabricated. The interconnected structure of CNS contributes to the formation of conductive paths in the TPU matrix, which brings about low percolation threshold of fillers in the TPU composites. Besides, CNS show superior reinforcement in TPU composites in terms of tensile modulus by comparison with CNTs and GNPs. However, the use of CNTs or GNPs in TPU composites enables retaining higher elongation at break (up to 1000%) by comparison with CNS. Therefore, hybrid fillers of CNS with CNT or GNP render tunable electrical conductivity and mechanical properties in the resultant TPU composites. In addition, these conductive elastomer composites show good piezoresistive properties with potential applications in stretchable strain sensors.