Multilayer steels have been developed to provide a novel route to achieving higher-performance steels by employing a high-strength steel and a high-ductility steel independently in the layer structure. In this article, a background to the development, design, fabrication, properties, and applications of multilayer steels are overviewed. Multilayer steels exhibit improved combinations of strength and ductility compared with existing monolithic steels and also excellent deformation behaviors under high-strain-rate deformation as well as good formability. Those improved performances of multilayer steel are achieved by increased interfacial toughness between the layers and decreased thickness of the brittle steel layers according to the fracture toughness of the brittle steel and the strength of the ductile steel. The concept of multilayer steels is extended by applying different combinations of components, such as Mg-steel multilayer composite.