Kenaf composites have a high strength-to-weight ratio, but weak fiber�matrix interface bonding limits their automotive use. To address this, a novel technique was developed to fabricate multiphase composites using graphene nanoplatelets (GNPs), kenaf fibers, and an epoxy matrix. The composites were made using vacuum infusion molding, with the GNPs exfoliated using a bath sonicator for uniform dispersion. The composites modified with 0.2 wt GNP showed the most significant improvement in mechanical properties. Specifically, these composites exhibited a 30.5 increase in tensile strength, a 61.5 increase in tensile modulus, a 17.6 increase in flexural strength, a 22.7 increase in flexural modulus, a 35.1 increase in interlaminar shear strength, and a 17.1 increase in fracture toughness. Additionally, the water absorption resistance of the multiphase composites improved by up to 7. These improvements were attributed to the uniform dispersion of GNPs and improved interlocking with the fiber surface. The developed composite has the potential for interior parts (such as dashboards, interior walls, and luggage compartments) in the automotive vehicle. © 2023