Copper matrix composites prepared via traditional methods face mechanical property and electrical conductivity trade-off problems. In this study, TiB₂/Cu−Cu heterogeneous laminated composites with submicron lamellar thicknesses were prepared via flake powder metallurgy (FPM) using gas-atomized in situ composite powders as raw material. By thermal mismatch strengthening, and the geometrically necessary dislocations (GNDs) generated by mechanically incompatible deformation between adjacent heterogeneous lamellae and their interaction with statistically stored dislocations (SSDs), the as-prepared TiB₂/Cu−Cu submicron laminated composites (SLCs) exhibit significantly enhanced mechanical properties. At the same time, the interaction and propagation of multimode cracks provide extrinsic toughening for SLCs. The pure Cu lamellae with low density grain boundaries and dislocations and no TiB₂ particles provide a channel with little electron scattering for the rapid transport of carriers, thereby ensuring high electrical conductivity.