This paper addresses fabrication, structure, and hardness characteristics of nanotwinned (ntw) copper-graphene composites. The composites were fabricated by electrodeposition from 1M CuSO₄·6H₂O mixed water-alcohol solution containing graphene-graphite mixture stabilized by non-ionic surfactant. We fabricated two-layer solids each consisting of ntw copper layer and ntw copper-graphene layer. The synthesized two-layer specimens were examined in nanoindentation tests and showed high hardness values up to 3 GPa. The maximum hardness value of 3 GPa is higher than those of pure ntw copper and copper-graphene composites, taken from the literature.