Lead-free flexoelectric piezoelectric metamaterials are created by applying an asymmetric chemical reduction to Na1/2Bi1/2TiO3-BaTiO3 ceramics. The reduction induces two gradient-generating mechanisms, curvature structure and chemical inhomogeneity, and enhances the flexoelectric effect. The ceramics behave like piezoelectric materials, exhibiting an enormous and high-temperature stable apparent piezoelectric response, outperforming existing lead-oxide-based piezoelectrics.