High-speed steel typically comprises a high carbon content with an abundance of alloying elements, leading to a solidified microstructure rich in carbides. The refinement of these carbides in the microstructure is the most effective method for enhancing the mechanical properties of high-speed steel, and it remains a primary focus of the high-speed steel research. The prevalent industrial production methods for high-speed steel include traditional casting and forging, powder metallurgy, and spray forming. Traditional casting and forging methods are often constrained by segregation issues, hindering the application of high-quality cast and forged high-speed steel. Powder metallurgy high-speed steel exhibits remarkable mechanical properties; however, its high production costs have restricted its broader development. Conversely, spray forming is an advanced manufacturing method characterized by cost effectiveness, efficient production, and environmental friendliness. Although China has successfully implemented the mass production of spray-formed tool and die steel, systematic research on the microstructure and properties of such steel in actual industrial preparation is lacking. This study conducts a comparative analysis of the microstructure and mechanical properties of the M3 high-speed steel prepared via three distinct methods: electroslag remelting, spray forming, and powder metallurgy. The experimental results show that although the different preparation methods exert minimal impact on the carbide type within the annealed microstructure of the M3 high-speed steel, they considerably affect the morphology, size, and distribution of the carbides. Spray-formed and powder metallurgy high-speed steels display a dispersed, particulate carbide distribution across transverse and longitudinal sections, with spray-formed steel exhibiting coarser carbide sizes. Electroslag remelted high-speed steel exhibits a network-like distribution of carbides in the transverse sections and a distinct banded arrangement in the longitudinal sections. The mechanical properties of powder metallurgy high-speed steel were superior to those of electroslag remelted and spray-formed high-speed steels. The more uniform and finer the distribution of carbides within the steel microstructure, the higher will be their hardness, bending strength, and impact toughness. Regarding wear resistance, spray-formed high-speed steel outperforms the others, which is attributed to the presence of large-sized MC-type carbides in its microstructure. These carbides not only provide better wear resistance, but also change the formation of the oxidation layer from diffusion mechanism to sintering mechanism, thereby reducing crack propagation in the matrix and enhancing wear resistance. This study delves into the carbide precipitation behavior of the M3 high-speed steel during the spray forming process based on the microstructural characteristics of the spray-formed steel.