By using density functional theory, we have investigated the geometrical structures, electrophilic properties, magnetic properties, and fragmentation channels of FeXn (X = Cl, Br; n = 1–6) clusters as well as the “mixed species” that contain interhalogen compounds. Our main objectives are to design new iron‐based magnetic superhalogens and to explore whether the interhalogen compounds are suitable for the superhalogen ligand. By calculating their adiabatic electron affinities (AEAs) and vertical detachment energies (VDEs), we found that both FeCln and FeBrn can be classified as superhalogens for n ≥ 3. Among mixed species, FeClF3, FeBrF3, FeClF5, and FeBrF5 are superhalogens, but their AEA values are still smaller than those of the correspondingly sized FeFn clusters. Their superhalogen properties are further supported by the natural population analysis (NPA) charge distribution and the HOMO of anions. However, in mixed species, the extra electron and HOMO do not uniformly delocalize over the different halogen atoms. This might be the reason why FeXYn possesses relatively small AEA values. In addition, we also studied the superhalogen salts formed with these superhalogen anions and Na+, which greatly enhance the reliability of our obtained superhalogens.