Recent studies to explore the enhanced electromagnetic properties of TiN and TiC reported that TiNC has a good performance in EM wave absorption. We prepared TiNC with quantificational percentages of carbon doping in this work. Nanotitanium oxide precursor was prepared via sol–gel method, then submicron TiN(1–x)C x with different carbon content (x = 0, 0.2, 0.4, 0.6, 0.8) was obtained via solid–gas reaction by nitriding at 900 °C with nitrogen and carbon doping at 1700 °C with argon. The composition and structure of TiN(1–x)C x change with the increase of carbon content, the lattice distortion and dipole moments were introduced into TiN crystal via carbon doping which leads to optimization of the electromagnetic properties. The influence of carbon doping was analyzed, and at carbon = 0.8, the attenuation factor “α” and impedance matching “Δ” of the sample achieved a better balance that results in a better wave absorbing effect. The resulting bandwidth lower than −10 dB is in the range 11.1 to 13.6 GHz, and the reflection loss reached to −40.1 dB at 12.4 GHz with the sample thickness of 1.32 mm. The frequency of maximum reflection loss obeys the quarter-wavelength matching model. TiN(1–x)C x shows good electromagnetic absorbing properties and it is in accordance with the “thin, light, wide, strong” application requirements of microwave absorption materials.