The BiFeO₃-based film is one of the most promising candidates for lead-free piezoelectric film devices. In this work, the 1 μm-thick Bi(Fe0.93Mn0.05Ti0.02)O₃ (BFMT) films are grown on the ITO/glass substrate using a sol-gel method combined with spin-coating and layer-by-layer annealing technique. These films display a large saturated polarization of 95 μC/cm², and a remanent polarization of 70 μC/cm². Especially, the films are self-poled caused by an internal bias field, giving rise to asymmetric polarization-electric field (P?E) loops with a positive shift along the x-axis. A stable self-polarization state is maintained during the applied electric field increasing to 1500 kV/cm and then decreasing back. The weak dependence of P?E loops on frequency (1–50 kHz) and temperature (25–125°C) indicate that the internal bias field can be stable within a certain frequency and temperature range. These results demonstrate that the self-polarized BFMT thick films can be integrated into devices without any poling process, with promising applications in micro-electro-mechanical systems.The BiFeO₃-based film is one of the most promising candidates for lead-free piezoelectric film devices. In this work, the 1 μm-thick Bi(Fe0.93Mn0.05Ti0.02)O₃ (BFMT) films are grown on the ITO/glass substrate using a sol-gel method combined with spin-coating and layer-by-layer annealing technique. These films display a large saturated polarization of 95 μC/cm², and a remanent polarization of 70 μC/cm². Especially, the films are self-poled caused by an internal bias field, giving rise to asymmetric polarization-electric field (P?E) loops with a positive shift along the x-axis. A stable self-polarization state is maintained during the applied electric field increasing to 1500 kV/cm and then decreasing back. The weak dependence of P?E loops on frequency (1–50 kHz) and temperature (25–125°C) indicate that the internal bias field can be stable within a certain frequency and temperature range. These results demonstrate that the self-polarized BFMT thick films can be integrated into devices without any poling process, with promising applications in micro-electro-mechanical systems.