<p>A strengthening strategy for 05Cr17Ni4Cu4Nb stainless steel was developed by laser directed energy deposition (L-DED) with nano-WC reinforcement. During L-DED, laser-induced decomposition of WC released W and C, promoting the precipitation of M₇C₃, M₂₃C₆, and NbC carbides. The nano-WC particles also acted as heterogeneous nucleation sites, facilitating the formation of nanoscale Cu-rich precipitates. The synergistic effect of carbides and Cu-rich phases effectively suppressed grain growth, strengthened grain boundaries, and impeded dislocation motion, thereby achieving microstructural refinement and enhanced resistance to deformation. Meanwhile, WC decomposition in the molten pool induced partial reverse transformation of martensite into retained austenite, which can dissipate frictional energy and reduce the spallation of brittle phases, further improving wear performance. Compared with the as-received 05Cr17Ni4Cu4Nb stainless steel, the composite with 16 wt. % WC showed an approximately 8.7% increase in microhardness and achieved a steady-state friction coefficient of 0.234. The superior wear resistance is mainly attributed to the synergistic precipitation-strengthening and dislocation-pinning effects of Cu-rich phases and nano-carbides, complemented by the toughening effect of retained austenite.</p>