Laser surface alloying of Ti6Al4V with different Cu contents (6, 8, 13 and 17 wt%) was successfully achieved using a high-power diode laser. With a higher Cu content, the grain size of the laser surface-alloyed Ti6Al4V specimens became finer, with more intermetallic phases (IMPs) formed and the hardness increased up to 646 ± 18 HV. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were conducted to study the corrosion behavior of the laser surface-alloyed specimens in a 0.9 wt% NaCl solution at 37 °C. It was found that the specimen alloyed with 6 wt% Cu showed the mild micro-galvanic effect between CuTi and α-Ti. The specimen with 17 wt% Cu had the highest content of IMPs and possessed the lowest corrosion resistance due to the most significant micro-galvanic effect between the IMPs (cathode) and the α-T / β-Ti matrix (anodes). With an appropriate Cu content, laser surface-alloyed Ti6Al4V can also act as hard and corrosion resistant components possessing a high anti-bacterial efficacy by virtue of Cu.