In this study, a relaxor ferroelectric ceramic, 0.67Pb(Mg_1/3Nb_2/3)O₃–0.33PbTiO₃ (PMN–PT), was synthesized by a molten-salt growth method with lower remnant polarization and slimmer hysteresis loops than traditional ferroelectric ceramics. The PMN–PT particles remained homogeneously dispersed in the composite and adhered tightly to a poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) matrix due to the modification of the particles with dopamine. The composites had a maximum dielectric constant of 65.1 and a low dielectric loss of less than 0.037 at 1 kHz. Due to the low remnant polarization of the relaxor ferroelectric ceramic of PMN–PT, the energy density of the composites significantly increased. The discharged energy density of the sample with 50 vol% PMN–PT was 4 times that of P(VDF-HFP) at 80 kV mm⁻¹. It was demonstrated that the dopamine functionalized PMN–PT/P(VDF-HFP) composite was a potential dielectric material with potential future applications in energy storage.