Ultrahigh temperature ceramics, such as carbide, boride, and MAX phase, exhibited exceptional high-temperature thermomechanical properties. Also, the emerging high entropy materials have indicated superior radiation tolerance. Therefore, high entropy ceramics (HECs) are supposed to be excellent candidate materials for advanced nuclear reactors. However, the radiation response of HECs is still not well investigated. Herein, we fabricate bulk HECs by mechanical alloying and spark plasma sintering (SPS). The HECs are irradiated by heavy ions and helium ions under various irradiation conditions. The radiation hardening is investigated by nanoindentation. The microstructural evolution, including radiation-induced dislocation loops, cavities, segregation, phase stability etc., is interrogated using analytical scanning/transmission electron microscopy (S/TEM), and atom probe tomography (APT). The radiation response of HECs will be compared with the binary ceramics. The results of this work will provide insights into the radiation behavior of HECs under extreme irradiation environments.