As-deposited (Fe, FePt, FePtCu)–C nanocomposite films with fixed C atomic fraction xc = 47 fabricated using facing-target sputtering method at room temperature are composed of ∼ 2–3‐nm amorphous metal granules buried in a‐C matrix. Annealing at high temperatures turns the amorphous granules into α‐Fe, α‐Fe- and L10-structured FePt, and L10-ordered FePtCu for Fe–C, FePt–C, and FePtCu–C films, respectively, and makes a‐C preferential graphitization. As-deposited granules are superparamagnetic at 300 K, and ferromagnetic at 5 K. The zero-field-cooled (ZFC) and field-cooled (FC) curves reveal that there exist strong intergranular interactions at temperatures below 300 K, and the size distribution of granules becomes broad by Pt and Cu addition. The M‐H loop of annealed Fe31Pt22C47 films exhibits a two-step saturation behavior because of the coexistence of soft and hard ferromagnetic phases. As the Cu atomic fraction is 14%, the coercivity of annealed Fe23Pt16Cu14C47 films reaches a large value of ∼ 11.2 kOe at 5 K and decreases to ∼ 7.2 kOe at 300 K.