Maraging steels are martensitic steels that are strengthened by the precipitation of nano-sized intermetallic phases. Severe plastic deformation is known to influence diffusion, stability and properties of metallic materials. The goal of this study is to reveal the influence of severe plastic deformation on the hardness and the precipitation behavior of a Co-free maraging steel. For this study the as-quenched material was deformed with high-pressure torsion. Afterwards, a series of heat treatments were conducted. The hardness increase was measured and correlated with micro-to-nanoscale microstructural characteristics, focused on the precipitate characterization with atom probe tomography. Severe plastic deformation transformed the microstructure to a globular microstructure, delayed and minimized austenite reversion as well as accelerated and influenced the precipitation reaction, affecting the size, morphology and type of intermetallic phases.