Ceramics typically have very high hardness, but suffer from poor toughness. Here, we use graphene to enhance the toughness of bulk boron carbide ceramics. The reduced graphene oxide ( rGO) platelets are homogenously dispersed with boron carbide particles after sintering at 1350 degrees C, under high pressure of 4.5 GPa with a multi-anvil apparatus. Fracture toughness of the composites is increased similar to 131% ( from similar to 3.79 to similar to 8.76 MPa m 1/ 2) at 1.5 vol% rGO platelets as a result of a toughing effect of graphene along with a little sacrificing of the hardness and elastic modulus, compared with those of pure boron carbide. The remarkably enhanced fracture toughness in the boron carbide ceramics is associated with graphene sheets crack bridging and graphene interface sliding effect. This study holds much significance for the understanding and development of high-performance graphene reinforcing ceramics.