Ceramics of quasi-binary concentration section ($x$ = 0.50, 0.1 $\le y\le$ 0.2, $\mathrm{\Delta }y$ = 0.025) of the ternary solid solution system (1$-x-y)$BiFeO₃–$x$${\text{PbFe}}_{0.5}$${\text{Nb}}_{0.5}$O₃–$y$PbTiO₃ were prepared by the conventional solid-phase reaction method. By using X-ray diffraction technique, the phase diagram of the system was constructed, which was shown to contain the regions of cubic and tetragonal symmetry and the morphotropic phase boundary between them. Grain morphology, dielectric and piezoelectric properties of the selected solid solutions were investigated. The highest piezoelectric coefficient $d_{33}$= 260 pC/N was obtained. Dielectric characteristics of ceramics revealed ferroelectric relaxor behavior, a region of diffuse phase transition from the paraelectric to ferroelectric phase in the temperature range of 350–500 K.Ceramics of quasi-binary concentration section ($x$ = 0.50, 0.1 $\le y\le$ 0.2, $\mathrm{\Delta }y$ = 0.025) of the ternary solid solution system (1$-x-y)$BiFeO₃–$x$${\text{PbFe}}_{0.5}$${\text{Nb}}_{0.5}$O₃–$y$PbTiO₃ were prepared by the conventional solid-phase reaction method. By using X-ray diffraction technique, the phase diagram of the system was constructed, which was shown to contain the regions of cubic and tetragonal symmetry and the morphotropic phase boundary between them. Grain morphology, dielectric and piezoelectric properties of the selected solid solutions were investigated. The highest piezoelectric coefficient $d_{33}$= 260 pC/N was obtained. Dielectric characteristics of ceramics revealed ferroelectric relaxor behavior, a region of diffuse phase transition from the paraelectric to ferroelectric phase in the temperature range of 350–500 K.