Iron–cobalt (FeCo) alloys are highly desirable for their exceptional and adjustable physicochemical properties, particularly in the form of thin films. This study focuses on the growth of iron–cobalt (FeCo) alloy thin films using potentiostatic electrodeposition. The effects of applied voltage and FeCo stoichiometry on the morphology, structure, and magnetic properties of the films are investigated. The results indicate that the electrodeposition potential does not affect the overall stoichiometry or the structural and magnetic properties. However, it does impact film thickness and grain sizes. Higher applied potentials lead to thicker films with faster growth rates, as well as smoother and more homogeneous films with smaller grains. Films with different Fe:Co ratios (Fe90Co10, Fe50Co50, and Fe10Co90) are obtained, and their compositions have a direct impact on morphology, with the amount of Fe influencing film thickness, growth rates, and grain sizes. Increasing Fe content (50, 90%) leads to thicker films and smaller grains. Films with low Fe content (10%) exhibit a face-centered cubic (fcc) structural phase instead of the typical body-centered cubic (bcc) structure. All FeCo alloys display soft magnetic properties with characteristic coercivities, and the low Fe (10%) sample with the fcc structure exhibits the highest coercivity among all the samples. The nucleation and growth mechanisms are investigated using electrodeposition curves and the Scharifker and Hills model. Increasing the applied potential leads to thicker films and higher growth rates, with the nucleation mechanism identified as instantaneous nucleation in the diffusion-controlled regime.