In the present study, a Zn-Co-Al₂O₃ composite coating was applied on an St37 steel substrate using the electroplating method. To investigate the effect of electroplating current density on surface morphology, corrosion behavior of the coating, and the amount of alumina particles in the coating, various coatings were created at current densities of 15, 20, and 30 mA.cm^-2. Scanning Electron Microscopy (SEM) was used to examine the morphology of the coatings, and Potentiodynamic Polarization and Electrochemical Impedance Spectroscopy (EIS) tests were conducted to evaluate the corrosion resistance of the samples (uncoated steel and coated steel) in a 3.5 %wt NaCl solution. The results of microscopic analysis showed that as the electroplating current density increases, the amount of alumina particles in the coating decreases and the coating microstructure changes from a clustered structure with irregular grains to a multilayer structure with fine crystalline grains. The Tafel polarization test results indicated that the polarization resistance of the sample coated at the current density of 15 mA.cm^-2 (~5495 Ω) was higher than that of the coated samples at 20 (~3778 Ω) and 30 mA.cm^-2 (~2503 Ω), as well as the uncoated sample (~513 Ω). These results indicate that the coated sample at a current density of 15 mA.cm^-2 has higher corrosion resistance compared to the other samples.