In order to achieve combined mechanical and electrical properties, multi-walled carbon nanotubes (MWCNTs) reinforced Cu/Ti₃SiC₂/C nanocomposites were further processed by high-pressure torsion (HPT). The maximum microhardness values of central and edge from the composites with 1 wt.% MWCNTs reached HV 130.0 and HV 363.5, which were 43.9% and 39.5% higher than those of the original samples, respectively. With the same content of MWCNTs, its electrical conductivity achieved 3.42×10⁷ S/m, which was increased by 78.1% compared with that of original samples. The synergistic improvement of mechanical and electrical properties is attributed to the obtained microstructure with increased homogenization and refinement, as well as improved interfacial bonding and reduced porosity. The strengthening mechanisms include dispersion and refinement strengthening for mechanical properties, as well as reduced electron scattering for electrical properties.