The Mn doped 0.63Bi(Mg_1/2Ti_1/2)O₃–0.37PbTiO₃ (BMT–0.37PT–xMn, x = 0–0.01) thin films were deposited on Pt(1 1 1)/Ti/SiO₂/Si substrates by a sol–gel method. The effect of the Mn doping concentration on the structure and electrical properties of BMT–0.37PT thin films was studied. The X-ray diffraction data indicate that the B-site Mn substitution does not change the perovskite structure of the films. The X-ray photoelectron spectra show that Mn ions mainly exist as Mn³⁺ except for a few as Mn²⁺ for the 1 mol% Mn doped BMT–0.37PT film. Moreover, it was found that the addition of a small amount of Mn effectively reduces the dielectric loss and improves the resistivity of the films. The BMT–0.37PT–0.005Mn film exhibits lower leakage current density than the undoped BMT–0.37PT film such that saturated hysteresis loops can be achieved. As a result, the BMT–0.37PT–0.005Mn film exhibits the largest permittivity (ɛ_r ∼ 1271 at 1 kHz) and remanent polarization (P_r ∼ 17.4 μC/cm² at 100 Hz) in all studied compositions.