In this article, electrodeposited Ni-Al₂O₃ coatings were fabricated on the surface of a cylinder liner to enhance its corrosion resistance. The effect of current density on the surface morphology, phase structure, and corrosion resistance of the Ni-Al₂O₃ coatings was investigated using a scanning electron microscope (SEM), X-ray diffraction (XRD) instrument, and electrochemical workstation, respectively. The observed results show that a dense, flat morphology emerged on the surface of the Ni-Al₂O₃ coatings prepared under a current density of 3.5 A/dm². Furthermore, among three Ni-Al₂O₃ coatings, the Al content of the one prepared under a current density of 3.5 A/dm² was the highest, with a value of 5.4 wt.%. XRD patterns demonstrated that the average nickel grain size of the Ni-Al₂O₃ coatings prepared at 3.5 A/dm² was only 251.6 nm, which was obviously smaller than those deposited under current densities of 2.5 A/dm² and 4.5 A/dm². Meanwhile, the adhesion strength of the Ni-Al₂O₃ coatings prepared under a current density of 3.5 A/dm² was the largest, with a value of 40.9 N. Polarization curves indicated the corrosion potential of the Ni-Al₂O₃ coatings prepared under a current density of 3.5 A/dm² was the highest, with a value of −0.42 V, while the corrosion current density of the coatings fabricated under a current density of 3.5 A/dm² was the lowest, with a value of 2.17 × 10⁻⁷ A/cm². In addition, the corrosive mass loss of Ni-Al₂O₃ coatings manufactured at 3.5 A/dm² was only 2.8 mg, illustrating excellent corrosion resistance. This study could enhance the service life and corrosion resistance of cylinder liners in internal combustion engines.