Directed Energy Deposition (DED) additive manufacturing has been widely applied in mold, biomedical, and defense industries for the fabrication and repair of metallic components. However, during the DED process of STS316L alloy, oxidation phenomena induced by high-energy melting and solidification can lead to oxide scale formation and porosity, thereby degrading the expected performance of the manufactured parts. In this study, hexagonal boron nitride (hBN) was incorporated into STS316L alloy powder to suppress oxidation behavior and improve mechanical properties. Microstructural observations, high-temperature oxidation tests, hardness measurements, and wear evaluations were conducted on fabricated specimens. The results revealed that the addition of hBN effectively retarded the growth of oxide layers and reduced surface oxidation defects. Furthermore, both hardness and wear resistance were enhanced, leading to improved durability of the STS316L alloy. This work demonstrates the potential of hBN addition as an effective approach to simultaneously mitigate oxidation and enhance the mechanical performance of DED-processed STS316L components, providing promising implications for industrial applications.