Modification of the structural phase state of the surface layer of zirconium ceramics irradiated by high-power pulsed beams of carbon ions at a pulse energy density of 3 J/cm² is revealed using X-ray phase analysis and scanning electron microscopy. The analysis of roentgenograms indicates efficient formation of the high-temperature cubic modification of zirconium dioxide. The study of the depth distribution of oxygen ions using the secondary ion mass spectroscopy yields deficit of oxygen in the surface layer of the irradiated ceramics. A violation of the oxygen stoichiometry leads to a significant (by several orders of magnitude) increase in the conductivity of the samples under study. Mechanical characteristics (microhardness, nanohardness, and Young modulus) of the zirconium ceramics are determined after processing with high-power pulsed beams.