The electrocatalytic urea oxidation reaction (UOR) provides more economic electrons than water oxidation for various renewable energy‐related systems owing to its lower thermodynamic barriers. However, it is limited by sluggish reaction kinetics, especially by CO₂ desorption steps, masking its energetic advantage compared with water oxidation. Now, a lattice‐oxygen‐involved UOR mechanism on Ni⁴⁺ active sites is reported that has significantly faster reaction kinetics than the conventional UOR mechanisms. Combined DFT, ¹⁸O isotope‐labeling mass spectrometry, and in situ IR spectroscopy show that lattice oxygen is directly involved in transforming *CO to CO₂ and accelerating the UOR rate. The resultant Ni⁴⁺ catalyst on a glassy carbon electrode exhibits a high current density (264 mA cm⁻² at 1.6 V versus RHE), outperforming the state‐of‐the‐art catalysts, and the turnover frequency of Ni⁴⁺ active sites towards UOR is 5 times higher than that of Ni³⁺ active sites.