Black Aspergilli (Aspergillus section Nigri) are widely distributed in various habitats. They act as food spoilage organisms, human pathogens, and mycotoxin producers and are frequently encountered in indoor environments. Black Aspergilli, specifically A. niger, A. welwitschiae, and A. carbonarius, produce different ochratoxins and fumonisins. Ochratoxins are known to induce renal disorders following inhalation, which necessitates the determination of potential mycotoxin-producing species in our environment. This paper aimed to compare the diversity and species distribution of black Aspergilli in the indoor environments of six different countries using morphological and molecular methods. A total of 178 black Aspergillus isolates were identified from six countries. In contrast with results from previous studies, A. niger was not the only black Aspergillus detected in indoor air. Species distribution differed among countries, although the distribution in European countries (Croatia, Hungary, the Netherlands, and Turkey) with a temperate climate was considerably similar. The highest species diversity was observed in indoor samples from Thailand, while the lowest was found in Algeria. Potentially ochratoxin- and fumonisin-producing fungi were detected in the indoor air of all six countries. Further studies need to clarify the effect of these fungi and their mycotoxins on human and animal health.