<p>This study investigates the influence of processing parameters and heat treatment on the microstructure and mechanical properties of AISI H13 tool steel fabricated via laser powder bed fusion (LPBF). The microstructure comprises fully martensitic or ferrite/martensitic structures possibly due to the carbon evaporation during the manufacturing process. The observed microstructural changes, including the uneven formation of ferrite grains in the martensite structure, have minimal impact on the ultimate tensile strength (UTS). UTS is primarily governed by the size of martensitic laths and carbides, which are largely determined by the tempering temperature. Increasing the tempering temperature leads to an increase in lath size and carbide coarsening, resulting in a reduction in UTS. Elongation, on the other hand, is highly sensitive to manufacturing defects, such as porosity, as well as microstructural features, including the decomposed martensite and carbide size. Porosity reduces elongation, whereas increased tempering enhances elongation by promoting carbide coarsening. The microhardness exhibits significant variation, exceeding 200HV, primarily due to the presence of ferrite, carbide coarsening, and porosity. These factors collectively contribute to reducing the microhardness. Finally, statistical analysis of analysis of variance (ANOVA) validated these findings and assessed the effects of processing parameters and tempering temperature on mechanical properties and density. Additionally, response surface methodology (RSM) was used to predict elongation, relative density, and average microhardness based on processing parameters and tempering temperatures.</p>