Nitrogen (N) doping is an effective strategy for enhancing superconductivity in transition-metal carbides. Orthorhombic ${\mathrm{W}}_2\mathrm{C}$ has been experimentally synthesized and identified as an intrinsic superconductor. However, the influence of N doping on its superconducting and topological properties remains unclear. Herein, we systematically explore N doping in ${\mathrm{W}}_2\mathrm{C}$ via first-principles calculations and reveal that all considered ${\mathrm{W}}_2{\mathrm{C}}_{1-x}{\mathrm{N}}_x$ ($x=0$, 0.25, 0.5, 0.75, 1) compounds exhibit both stability and metallic character. The results show that N doping can reconstruct the electronic structure and drive the Lifshitz transition. Notably, the superconducting transition temperature $T_c$ exhibits a dome-shaped dependence on N concentration. Up to $x=0.75$, the increase in the density of states at the Fermi level $N\left(E_F\right)$, together with the softening of the low-frequency W-dominated phonon modes, enhances the electron-phonon coupling (EPC) strength $\lambda$ and raises $T_c$, whereas at $x=1$, the reductions in $N\left(E_F\right)$ and $\lambda$ lower $T_c$. Microscopically, the dominant EPC arises from the coupling between W-$5d$ electrons and low-frequency vibrations of W. Wannier-based $Z_2$ invariant reveals a doping-induced topological transition from nontrivial to trivial states with increasing N content. These findings provide microscopic insight into N-doping-controlled superconductivity and topological properties in ${\mathrm{W}}_2\mathrm{C}$, and offer theoretical guidance for designing tunable superconducting and topological transition-metal carbides.

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• Electronic structure
• Superconductivity
• Eliashberg theory
• First-principles calculations
• Wannier function methods