[en] B_4C composites containing 1–4 vol.% graphene nanoplatelet (GNP) were fabricated aiming at obtaining electrically conductive B_4C composites with high toughness. The electrical conductivity of B_4C composite was enhanced remarkably with the addition of only 2 vol.% GNPs. Besides, all the GNP/B_4C composites maintained high Vickers hardness. The fracture toughness kept increasing with the increase of GNPs volume fraction and a high value of 5.26 MPa·m"1"/"2 was obtained in GNP/B_4C composite with 4 vol.% GNPs. The main toughening mechanisms include GNPs pull-out, crack deflection and crack bridging.