Metal Cu has excellent electrical and thermal conductivity, but poor mechanical properties. Incorporating ceramic particles into the Cu matrix to prepare Cu-based composites is one of the most effective methods to improve the mechanical properties. This paper reports a simple and efficient one-step method for the electrochemical preparation of nano-Al2O3 reinforced Cu-based composite; the electrodeposition process and properties of the prepared materials were also studied. Scanning electron microscopy and energy dispersive spectroscopy measurements showed that the Al2O3 nanoparticles were uniformly dispersed in the Cu matrix of the electrodeposited Cu-Al2O3 composites. Incorporating Al2O3 nanoparticles affected the grain size and microstructure of the composites, improving the mechanical properties of the Cu matrix. Increasing the Al2O3 concentration in the electrolyte resulted in the grain size of the composites decreasing to a range of 40.8-98.5 nm. Meanwhile, the preferred orientation of the present composites changed from (111) to (220) crystal plane. The Cu-Al2O3 composite had a tensile strength of 509 MPa, a hardness of 220 Hv, and an elongation to failure of 23.88%, indicating that the material had a high tensile strength while maintaining excellent ductility. Compared with the original monolithic Cu, the performance of the Cu-Al2O3 composite was nearly doubled.