Abstract: The magnetic structure and phase transition in xBiFeO₃–(1 – x)SrTiO₃ solid solutions, where x is from 0.2 to 1.0 with a step of 0.1, are studied systematically with Mössbauer spectroscopy. The multiferroic BiFeO₃ was modified via incorporation of a perovskite SrTiO₃, and xBiFeO₃–(1 – x)SrTiO₃ solid solutions that possess both ferrimagnetic and ferroelectric properties at room temperature were prepared. X-ray diffraction data indicate that there are no any additional phases in the xBiFeO₃–(1 – x)SrTiO₃ systems, whereas Mössbauer data show that there is a mullinite (Bi₂Fe₄O₉), when amount x of SrTiO₃ in the solid solution is from 1.0 to 0.8. The Mössbauer spectra of the xBiFeO₃–(1 – x)SrTiO₃ system at room temperature show that when amount of BiFeO₃ in the solid solution decreases, the magnetic hyperfine field values decrease as well and the widths of absorption line increase due to the weakening of the magnetic exchange interaction. The Mössbauer spectra of the systems with x < 0.5 indicate that the solid solution is paramagnetic. A relationship between the intensity of Zeeman lines and an amount of BiFeO₃ in BiFeO₃–(1 – x)SrTiO₃ solid solution showed that the transition of this system to the paramagnetic state proceeded at room temperature, when x value was 0.4 (between x = 0.3 and 0.5).