AbstractThe concept of producing structure–function integrated wave‐absorbing ceramics by combining three‐dimensional (3D) printing with the precursor conversion method has sparked extensive discussion and research. However, the synergistic enhancement of both the mechanical and electromagnetic (EM) properties of structural wave‐absorbing ceramics remains an area requiring further exploration. In this study, we employed the direct ink writing (DIW) process and polymer‐derived ceramics (PDCs) method to fabricate SiOC/SiCN composites with excellent mechanical and EM properties, modified by the polymer infiltration pyrolysis (PIP) process. The results demonstrated that PIP significantly improved the mechanical properties of SiOC/SiCN composites. After one cycle of infiltration pyrolysis, the compressive strength of the material was 6.3 times that of the unmodified state, and after three cycles, the compressive strength reached 10.13 MPa, which was 12.8 times that of the original. Furthermore, after three cycles of infiltration pyrolysis, the material exhibited effective absorption across the entire X‐band range (8.2–12.4 GHz) for thicknesses of 4.0 mm and 4.5 mm, with a minimum reflection loss (RLmin) of −64 dB, showcasing excellent wave‐absorbing capabilities. This study provides an innovative solution for the synergistic enhancement of both mechanical and EM properties in structure–function integrated wave‐absorbing ceramics.