Laser-directed energy deposition of Ni-based WC composite coatings offers promise for wear-resistant applications. This study investigated the manner in which a stable magnetic field regulates the behavior of the melt pool to suppress defects, reveal microstructural evolution, and enhance tribological performance. Magnetically induced thermoelectric magnetohydrodynamic and Lorentz forces promote uniform WC distribution, suppress oxidation, and reduce defect formation. The refined and stabilized microstructure provides stronger interfacial integrity and improved dislocation arrangements. These changes markedly strengthen load-bearing capacity at the friction interface, leading to a reduction in oxidative spallation, lower debris accumulation, and enhanced resistance to plastic deformation. Consequently, the efficacy of magnetic field control in the design of high-performance wear-resistant coatings has been demonstrated.