In this study, to improve the electrical properties and impact strength of phenolic formaldehyde (PF) resin, PF-based composites were prepared by mixing graphene and the ionic liquid 3-decyl-bis(1-vinyl-1-imidazole-3-ium-bromide) (C[VImBr]) via hot blending and compression-curing processes. The graphene surface was modified using a silane coupling agent. The synergistic effect of graphene and C[VImBr] on the electrical properties, electromagnetic shielding efficiency, thermal stability, impact strength, and morphology of PF/graphene and PF/graphene/C[VImBr] composites was then investigated. It was found that the electrical conductivity of the composites significantly increased from 2.3 × 10 to 4.14 × 10 S/m with an increase in the graphene content from 0 to 15 wt %, increasing further to 0.145 S/m with the addition of 5 wt % C[VImBr]. The electromagnetic shielding efficiency of the composite increased from 4.70 to 28.64 dB with the addition of 15 wt % graphene, while the impact strength of the composites rose significantly from 0.59 to 1.13 kJ/m with an increase in the graphene content from 0 to 15 wt %, reaching 1.53 kJ/m with the addition of 5 wt % C[VImBr]. Scanning electron microscopy images of the PF/GNP/C[VImBr] composites revealed a rough morphology with numerous microcracks.