A new compositional family of relaxor ferroelectrics was investigated based on the high‐temperature Bi(Me)O3–PbTiO3 ferroelectric perovskite family. Compositions were fabricated near an estimated morphotropic phase boundary (MPB) of the xBiScO3–yPb(Mg1/3Nb2/3)O3–zPbTiO3 (xBS–yPMN–zPT) ternary system exhibiting high‐temperature relaxor properties of Tmax∼250°–350°C and ɛmax∼10 000–24 000 at 1 kHz. Analysis of the low‐field a.c. permittivity by a Vogel–Fulcher type dependence enabled key parameters of activation energy, EA, and freezing temperature, Tf, to be determined. The remanent polarization was studied over a broad temperature range and was observed to show classical ferroelectric square loop hysteresis behavior at temperatures T<Tf while slim loop hysteresis behavior was observed at temperatures Tf<T<Tmax. Pyroelectric current measurements were made and integrated to determine macroscopic polarization‐temperature dependence, and were in excellent agreement with the hysteresis data. The macroscopic polarization was found to drop off rapidly near the freezing temperature, Tf. At temperatures T>Tmax, the deviation temperature, TD, was obtained from Curie–Weiss analysis and found to be ∼600°C. A comparison of characteristic electrical properties was made between the high‐temperature perovskite relaxors and the classical complex lead relaxor compound, Pb(Mg1/3Nb2/3)O3 (PMN).