This study describes the correlation between microstructure and mechanical properties of an ultra-high-strength Fe86.7Cr4.4Mo0.6V1.1W2.5C4.7 (at.%) alloy manufactured under high cooling rates and pure conditions. The applied preparation conditions promote the formation of non-equilibrium phases such as martensite, retained austenite and special carbides already in the as-cast state. The carbides form a 3-dimensional skeleton-like structure between the retained austenite and the martensite. This hard and finely ramified carbide network distributed throughout the entire ingot is a specific characteristic of this alloy and important for its excellent mechanical properties. The material exhibits extremely high engineering compression strength of almost 5500 MPa combined with a large compression strain of about 23% due to deformation-induced martensite formation. Furthermore, the alloy possesses a high hardness and tensile strength in the as-cast condition. This combination of mechanical properties leads to an outstanding engineering material for a variety of structural applications in the automotive and tool manufacturing industry.