The synthesis of colloidal Cr³⁺-doped In₂O₃ NCs with the body-centered cubic bixbyte-type crystal structure, and Cr³⁺-doped SnO₂ NCs with the rutile crystal structure was described. Ligand-field electronic absorption spectroscopy suggests that Cr³⁺ dopants have quasi-octahedral coordination in both In₂O₃ and SnO₂ NC host lattices. Unlike free-standing nanocrystals, the nanocrystalline films fabricated from colloidal Cr³⁺-doped In₂O₃ and SnO₂ nanocrystals exhibit room temperature ferromagnetism. Analogous magnetic behavior suggests the same origin of ferromagnetic ordering in both materials. The observed ferromagnetism has been related to the existence of extended structural defects, formed at the interfaces between nanocrystals in nanocrystalline films. These structural defects are likely responsible for the formation of charge carriers which mediate the dopant magnetic moment ordering.