Low-power plasma-sprayed Cr/Al₂O₃ coatings have been developed for their potential application as broad bandwidth, thin thickness, lightweight, and strong microwave-absorbing materials. The dielectric and microwave absorption properties of the as-sprayed coatings were studied in the X-band (from 8.2 to 12.4 GHz). High complex permittivity of the coatings was obtained because of a large number of internal boundaries and the conductive networks. Meanwhile, a significant enhancement of microwave absorption properties of the coating was achieved due to the enhanced interfacial polarization and conductance loss. The reflection loss (RL) <−10 dB of the Al₂O₃–15Cr coating was obtained from 9.8 to 11.4 GHz by choosing an appropriate coating thickness, and an optimal minimum reflection loss (RL_min) of −45.35 dB was achieved at 10.3 GHz with a thin thickness of 1.32 mm.