Abstract(Fe48Pt52)1–xMnx‐C composite films with different x were fabricated using magnetron sputtering and post‐annealing at 550 °C. Proper Mn doping can improve the ordering of the face‐centered tetragonal (fct) FePt grains. The lattice constant ratio (c/a) first decreases, then increases with the increasing x. At x = 2.1%, the minimum c/a of 0.964 and the maximum ordering degree of 0.96 were obtained. All of the films are hard ferromagnetic. The maximum room‐temperature coercivity of the films is 7.5 kOe at x = 2.1% and 10‐kOe field, and the coercivity decreases from 13.3 kOe at 20 K to 10.1 kOe at 300 K under a 90‐kOe field. The reversal mechanism of the films is the coexistence of the domain wall motion and Stoner–Wolhfarth (S‐W) rotation modes.