•The hybrid material was synthesized from the in-situ growth of MNP on the GP surface.•The highest storage modulus sensitivity was obtained from the 0.5%v/v MNP-GP/PU with the value of 3.97 at the electric field strength of 2kV/mm.•The 0.5%v/v MNP-GP/PU exhibited the largest bending distance of 13.65mm under electric field of 500V/mm.•The 3.0%v/v MNP-GP/PU yielded the maximum bending distance of 15.35mm under magnetic field strength of 1650G.•The composites showed excellent recoverability and fast response under both electric and magnetic fields. Dual responsive material composed of magnetite nanoparticle (MNP) and graphene nanosheet (GP) as a hybrid filler and polyurethane (PU) as an electrostrictive matrix was fabricated. The hybrid filler was synthesized by the in-situ growth of MNP on the GP surface. The obtained hybrid particles behaved simultaneously as a superparamagnetic and conducting material. The hybrid-composites possessed electronic polarization and high response towards electric field, as they showed excellent recoverability and fast response during the temporal test under electric field. The highest storage modulus sensitivity was obtained from the 0.5%v/v MNP-GP/PU at the value of 3.97 under the applied electric field of 2kV/mm. In the deflection experiment, the 0.5%v/v MNP-GP/PU composite exhibited the largest bending distance of 13.65mm under the electric field of 500V/mm. On the other hand, the 3.0%v/v MNP-GP/PU yielded the maximum bending of 15.35mm under the magnetic field of 1650G.