Graphene or graphene-like carbon-reinforced copper matrix composites have gained extensive application prospects in aerospace and electronic fields due to their high electrical, thermal conductivity and excellent machining performance. The preparation of Cu/graphene composites at a relatively low temperature is highly demanded for practical applications. Herein, we develop an approach for synthesizing few-layer graphene (FLG) by contacting amorphous carbon (a-C) with Cu at a low annealing temperature of 300 ℃. It is found that the formation of FLG is mediated by the grain-boundary (GB) diffusion, interfacial diffusion and surface diffusion of carbon atoms simultaneously. The high density of Cu GBs can provide a fast diffusion path for “free” C atoms in the a-C sublayer, and the graphene layer was formed at the Cu GBs, at the Cu/a-C interface and on top of the Cu layer where carbon atoms are present. The Cu-induced growth of graphene at low temperatures may provide a promising support for synthesizing Cu/graphene composites in the future.