Despite strong interest from many industrial sectors driving demand and advancements in laser additive manufacturing (LAM) of steels, some issues remain as barriers limiting the current industrial applications, such as defects, residual stress, scattered, inadequate or/and anisotropic properties. To overcome these problems, several effective approaches have been developed to control and/or enhance the properties of LAM produced steel components. To help researchers and engineers attain up-to-date information and knowledge in this rapidly growing area, the present work provides an overview of current research in LAM of steels, in particular austenitic steels, ferritic steels, duplex steels and martensitic steels, with a focus on understanding the interrelation between process, microstructure and mechanical properties. This review also includes substantive discussions on the effects of processing parameters, their interactions and post-LAM treatments on the metallurgy, microstructure and properties. In addition, the advances, ongoing challenges and outlooks in LAM of steels are highlighted.