After field cooling (FC) alternating current poling (ACP), we investigated the dielectric and piezoelectric properties of [001]_pc-oriented 0.24Pb(In_1/2Nb_1/2)O₃ (PIN)-0.46Pb(Mg_1/3Nb_2/3)O₃ (PMN)- 0.30PbTiO₃ (PT) (PIMN-0.30PT) single crystals (SCs), which were manufactured by continuous- feeding Bridgman (CF BM) within morphotropic phase boundary (MPB) region. By ACP with 4 kV_rms/cm from 100 to 70 ℃, the PIMN-0.30PT SC attained high dielectric permittivity $({\epsilon }_{33}^T\text{/}{\epsilon }_0)$ of 8330, piezoelectric coefficient (d₃₃) of 2750 pC/N, bar mode electromechanical coupling factor k₃₃ of 0.96 with higher phase change temperature (T_pc) of 103 ℃, and high Curie temperature (T_C) of 180 ℃. These values are the highest ever reported as PIMN-xPT SC system with T_pc > 100 ℃. The enhancement of these properties is attributed to the induced low symmetry multi-phase supported by phase analysis. This work indicates that FC ACP is a smart and promising method to enhance piezoelectric properties of relaxor-PT ferroelectric SCs including PIMN-xPT, and provides a route to a wide range of piezoelectric device applications.