As-deposited Fe–C granular films doped with N fabricated using facing-target sputtering at room temperature are amorphous. Annealing at temperatures ranging from 200 °C to 600 °C causes the crystallization of metal granules, the enlargement of the particle size from ~2 nm to ~50 nm and the decrease of the N atomic fraction. With the increasing nitrogen partial pressure (PN), the dominant phases of the particles in 600 °C annealed films develop from N-poor phases to N-rich phases, and the CN matrix still retains the amorphous state after the annealing. Meanwhile, high-temperature annealing turns superparamagnetism of the as-deposited films synthesized at PN < 0.1 Pa and paramagnetism at PN ≥ 0.1 Pa into ferromagnetism. The saturation magnetization of 600 °C annealed films decreases with the increasing PN, and both their saturation magnetization and coercivity drop with the rise of measuring temperature. In addition, the coercivity of the films increases with increasing annealing temperature initially and then declines due to the contribution of phase segregation and interparticle interactions.