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Abstract Achieving substantial electrostrain alongside a large effective piezoelectric strain coefficient (d₃₃*) in piezoelectric materials remains a formidable challenge for advanced actuator applications. Here, a straightforward approach to enhance these properties by strategically designing the domain structure and controlling the domain switching through the introduction of arrays of ordered {100}<100> dislocations is proposed. This dislocation engineering yields an intrinsic lock‐in steady–state electrostrain of 0.69% at a low field of 10 kV cm⁻¹without external stress and an output strain energy density of 5.24 J cm⁻³in single‐crystal BaTiO₃, outperforming the benchmark piezoceramics and relaxor ferroelectric single‐crystals. Additionally, applying a compression stress of 6 MPa fully unlocks electrostrains exceeding 1%, yielding a remarkabled₃₃* value over 10 000 pm V⁻¹and achieving a record‐high strain energy density of 11.67 J cm⁻³. Optical and transmission electron microscopy, paired with laboratory and synchrotron X‐ray diffraction, is employed to rationalize the observed electrostrain. Phase‐field simulations further elucidate the impact of charged dislocations on domain nucleation and domain switching. These findings present an effective and sustainable strategy for developing high‐performance, lead‐free piezoelectric materials without the need for additional chemical elements, offering immense potential for actuator technologies. 

Defects are essential to engineering the properties of functional materials ranging from semiconductors and superconductors to ferroics. Whereas point defects have been widely exploited, dislocations are commonly viewed as problematic for functional materials and not as a microstructural tool. We developed a method for mechanically imprinting dislocation networks that favorably skew the domain structure in bulk ferroelectrics and thereby tame the large switching polarization and make it available for functional harvesting. The resulting microstructure yields a strong mechanical restoring force to revert electric field–induced domain wall displacement on the macroscopic level and high pinning force on the local level. This induces a giant increase of the dielectric and electromechanical response at intermediate electric fields in barium titanate [electric field–dependent permittivity (ε₃₃) ≈ 5800 and large-signal piezoelectric coefficient (d₃₃*) ≈ 1890 picometers/volt]. Dislocation-based anisotropy delivers a different suite of tools with which to tailor functional materials.