Powder samples of Y3Al5−xFexO12 and Y3(YAl4−x)BFexO12 garnets with iron concentrations between 0.02 ≤ x ≤ 0.4 were investigated by means of magnetization measurements and Mössbauer spectroscopy. The results show that paramagnetism, antiferromagnetism, and ferromagnetism coexist in all samples at room temperature. The relative area of the ferromagnetic component was found to show a maximum at x = 0.04 and to diminish with raising the level of iron doping to x ≥ 0.1. Postannealing the samples in air did not result in a significant alteration of the Mössbauer spectra, but it decreased the bulk ferromagnetism considerably due to elimination of oxygen vacancies. We propose that the induced ferromagnetism at low iron doping rates can be discussed in the frame of the dilute ferromagnetism model for insulators, and so iron-doped yttrium aluminum garnets may represent one of novel room temperature dilute ferromagnetic materials.