Functionally graded materials (FGMs) represent a class of novel materials in which the chemical composition and/or microstructure are gradually modified along one or more spatial directions. This leads to a gradual change of functional properties, which can be tailored for specific requirements and to enhanced part performance. FGMs can be realized using a variety of processing methods. Powder-based Additive Manufacturing technologies such as Laser Directed Energy Deposition of Metals (DED-LB/M) offer the potential to simultaneously process multiple powder materials and to effectively adapt the material composition by means of so-called in-situ alloying. In this study, a duplex stainless steel (DSS) powder was in-situ alloyed with elemental chromium, nickel, and molybdenum powder during DED-LB/M processing. With this approach, two different types of functionally graded cubic structures were generated, a quasi-continuous gradation in build direction with increasing proportion of the respective elemental powder and a core-shell structure with a discontinuous change in composition. Chemical analysis of the generated specimens by means of optical emission spectroscopy and energy dispersive X-ray spectroscopy demonstrated that the target composition can be adjusted precisely via in-situ alloying. The microstructural change was investigated by optical and scanning electron microscopy on cross sections and correlated with the compositional change. Hardness measurements showed that hardness increases with the addition of chromium and in particular with the addition of molybdenum to the DSS. In-situ alloying with increasing nickel content reduced the resulting material hardness. Furthermore, the determination of the critical pitting corrosion temperature confirmed an increased corrosion resistance by the addition of chromium. This approach demonstrates the possibility of spatially varying the chemical composition of a DSS to generate structures with tailored quasi-continuous and discontinuous material property transitions.