Layered ceramics can simultaneously achieve high toughness and strong microwave absorption. In this work, layered Si₃N₄–SiC/boron nitride (BN) ceramics were prepared by tape casting and hot pressing, and the effect of microsized SiC content on their mechanical and microwave absorption properties was investigated. The results show that the microsized SiC content has little effect on the mechanical properties of layered Si₃N₄–SiC/BN ceramics. All layered ceramics exhibited excellent mechanical properties, with flexural strengths exceeding 600 MPa and apparent fracture toughness exceeding 20 MPa·m^1/2. The layered ceramics containing 30 wt% SiC showed the best attenuation within the X-band (8.2–12.4 GHz), with a minimum reflection loss (RL) of −51.3 dB and an effective absorption bandwidth (EAB) of 0.84 GHz. Simulations show that superlayered architectures composed of layered ceramics loaded with different SiC contents can further improve microwave absorption, with the designed bilayer structure achieving an RL_min of −34 dB and an EAB of 3.2 GHz in the X-band. This work lays a foundation for further optimization and fabrication of high-performance microwave absorption ceramics via structural design.