In this study, a novel (Ti,Ta,Nb,Zr,Hf,W,V,Mo)(C,N) high-entropy carbonitride ceramic (HECN), with a dual-phase structure comprising (Ti,Ta,Nb,W,V,Mo)(C,N) and (Ti,Ta,Nb,Zr,Hf)(C,N), was synthesized for the first time via in situ carbothermic reduction-nitridation and rapid hot pressing sintering. The microstructure, mechanical properties, and wear resistance of HECN were subsequently analyzed. The dual-phase structure of high-entropy ceramics should be caused by the multi-component cation occupancy. Interestingly, the increased sintering temperature could accelerate the formation of dual-phase structure in high-entropy ceramics. Moreover, increasing the sintering temperature enhanced the densification process, hardness and fracture toughness of ceramics. The HECN sintered at 1800°C demonstrates the high hardness of 22.81   GPa, a fracture toughness value of 3.66   MPa·m 1/2 and a wear rate of 0.56·10 -7 mm 3/Nm. This dual-phase high-entropy ceramic material exhibits significant potential for applications in cutting tools and wear-resistant components.