Oman has a diverse landscape, consisting of vast deserts, mountains, coastal areas, and, in the south, meadows and forests. In 2016, a checklist of 318 fungal species recorded in Oman was compiled. More than 100 plant pathogenic and other fungi have been described in the country since the first checklist. Furthermore, numerous nomenclatural changes have been made in the taxonomy of fungi over the past decade. Therefore, an updated outline of the fungi of Oman appears to be essential for various research purposes in the country, including systematics and diversity studies, agricultural relevance, and quarantine and biosecurity measures. The current updated outline lists 426 fungal species, belonging to 221 genera, 119 families, 65 orders, 26 classes, and 7 phyla. Details of each recorded species in Oman are provided, including the source of isolation, the area of occurrence, the nature of the fungus (pathogen, saprobe, symbiotic, biocontrol), and with relevant references.