ZrC Ultra-High Temperature Ceramic is a promising material for future extreme environment applications. However, its susceptibility to oxidation at elevated temperatures poses a significant challenge. There remains unresolved controversy in literature regarding its oxidation kinetics and activation energies. The temperature, oxygen pressure and time effects on the oxidation and passivation of ZrC are still not fully understood. To address these questions, we fabricated near-stoichiometric ZrC ceramic via spark plasma sintering (SPS) and for the first time investigated the temperature-oxygen pressure-time (T-P-t) dependent oxidation kinetics of SPS-sintered ZrC. A three-stage oxidation mechanism including a passivation stage was reported. The study also revealed the complexity of activation energy dependence on temperature and pressure within the 3D T-P-t space. Additionally, it uncovered the conditions necessary to maintain the passivation of ZrC. These findings provide valuable insights for future design of oxidation-resistant ZrC and carbides, paving the way for advancements in materials for extremes.