Nanoscale domains and structural disorder are important phenomena in lead-free rare-earth-substituted bismuth ferrite in the vicinity of the morphotropic phase boundary (MPB). This work highlights substitution-driven transitions in (Bi_1-xPr_x)FeO₃ (x = 0.05–0.25) polycrystalline ceramics from ferroelectric (FE) rhombohedral R3c to antiferroelectric (AFE) orthorhombic Pbam, then nonpolar orthorhombic Pnma phases as the system crosses over the MPB, identified by the 12{ooo}, 12(011), 14{111}, and 12{100} electron superlattice diffraction patterns. Enhanced ferromagnetic (FM) magnetizations near the MPB may result from a minor Fe⁴⁺ valence state and structural disorder. Sequential temperature-dependent phase transitions were observed and the orthorhombic Pnma phase becomes a dominant phase upon heating. The decreased O 2p–Fe 3d orbital hybridization plays a critical role for substitution-driven and thermally-activated structural transitions in the vicinity of the MPB. [Full article]