In this study, wear-resistant and corrosion-resistant cobalt-based Stellite 6 coating were fabricated on 17-4PH steel by laser cladding with varying Y₂O₃ content (0wt%, 0.3wt%, 0.6wt%, and 0.9wt%). The effects of Y₂O₃ addition on the microstructure, microhardness, wear resistance, and corrosion resistance of the laser-cladded Stellite 6 samples were investigated. The results indicate that the addition of Y₂O₃ changes the grain structure from coarse columnar grains to fine, uniform equiaxed grains. The sample with 0.6wt% of Y₂O₃ exhibits an average grain size of 54.6 μm, representing a maximum grain refinement of 66.0% compared to the sample without of Y₂O₃ addition. Furthermore, Y₂O₃ particles are mainly dispersed in the interdendritic regions of the Stellite 6 alloy samples, forming a particle layer in front of the dendrite grains, which inhibits grain movement and solute atom diffusion. The sample with 0.6wt% of Y₂O₃ addition shows the highest microhardness, with an average value of 532 HV. Due to the smallest grain size and spacing between Y₂O₃ particles, it also demonstrates the best wear resistance and corrosion resistance performance. Compared to the sample without Y₂O₃ addition, the maximum microhardness increases by 22.6%, the wear rate decreases by 72.2%, the corrosion potential increases by 25.6%, and the corrosion current density decreases by 39.8%.