In this work, we demonstrate that xPb(In1/2Nb1/2)O3-(1-x-y)Pb(Mg1/3Nb2/3)O3-yPbTiO3 [110]-poled domain-engineered relaxor single crystals can be dynamically and reversibly driven through a ferroelectric–ferroelectric phase transition exhibiting a highly enhanced piezoelectric response in a wide range of frequencies. Realization of this phase switching requires an applied compressive stress close to the critical values for the inter-ferroelectric phase transition, which can then be induced by a relatively small electric field (0.2 kV/mm). The required critical stress was established by in situ stress and x-ray diffraction measurements. The effective d32 coefficient measured dynamically up to 70 Hz was shown to be consistently twice that of the linear piezoelectric mode measured below the phase transformation region. The crystal was installed into a prototype transducer based on a Tonpilz configuration. The performance of the transducer was tested in water and showed up to 15 dBSPL higher acoustic power radiated when the crystal was driven through the phase transition than when operating in the linear piezoelectric regime.