Ultrahigh-temperature ceramics (UHTCs) are prominent candidates for use in thermal protection systems in the aerospace and nuclear industries. This study introduces a nitrogen-doped zirconium carbide that demonstrates remarkable ablation resistance, outperforming conventional carbide ceramics. The oxidation mechanisms of this material are elucidated through experimental and ab initio molecular dynamics simulations, representing the first analysis of such ultrahigh melting point ceramics from the perspective of structural development during the oxidation process. Transmission electron microscopy (TEM) analysis revealed the precipitation of nanocarbon and Zr–C–N–O phases at the interface between the oxidized and unoxidized regions following nitrogen doping. Nitrogen atoms preferentially combine with zirconium atoms at temperatures below the melting point of the oxide, forming robust Zr-C-N-O oxide network structures. These structures minimize oxide loss and maintain integrity during ablation, enhancing the material's performance in extreme environments. This study underscores nitrogen doping as a promising strategy to improve the ablation resistance of UHTCs, offering valuable insights for their application under demanding conditions.