High-entropy boride-silicon carbide (HEB-SiC) ceramics were fabricated using boride-based powders prepared from borothermal and boro/carbothermal reduction methods. The effects of processing routes (borothermal reduction and boro/carbothermal reduction) on the HEB powders were examined. HEB-SiC ceramics with > 98％ theoretical density were prepared by spark plasma sintering at 2000 ℃. It was demonstrated that the addition of SiC led to slight coarsening of the microstructure. The HEB-SiC ceramics prepared from boro/carbothermal reduction powders showed a fine-grained microstructure and higher Vickers' hardness but lower fracture toughness value as compared with the same composition prepared from borothermal reduction powders. These results indicated that the selection of the powder processing method and the addition of SiC phase could contribute to the optimal preparation of high-entropy boride-based ceramics.