Fe–C granular films with different Fe volume fraction xv were fabricated using a DC facing-target sputtering system at room temperature and subsequently annealed at different temperatures. X-ray diffraction and selected area electron diffraction analyses indicate that as-deposited and low-temperature annealed () samples are composed of amorphous Fe and C, and higher temperature annealing makes the amorphous Fe transform to α-Fe, which is also confirmed by high-resolution transmission electron microscopy. Magnetic measurements indicate that at room temperature the as-deposited Fe–C (xv = 58) granular films are superparamagnetic and annealed ones are ferromagnetic. The coercivity of 100 nm thick Fe–C (xv = 58) granular films increases with annealing temperature (for 1 h) and time (at 450 °C). The coercivity of the 100 nm thick Fe–C (xv = 58) samples annealed at temperatures ranging from 400 to 500 °C decreases linearly with measuring temperature T, signalling a domain wall motion mechanism. For the samples annealed at 550 °C, the change of in-plane coercivity with T satisfies the relation , reflecting that this system behaves better as a set of Stoner–Wohlfarth particles. It was also found that there exists a critical thickness ( nm) for the 450 °C annealed (for 1 h) Fe–C (xv = 58) granular films with thickness in the range 100–200 nm, below and above which the magnetization reversal is dominated by domain wall motion and by Stoner–Wohlfarth rotation, respectively.