Fungi are pathogens that affect humans, animals, food, and plants. Many strains are resistant to currently available antifungals, which are also associated with high toxicity and can cause environmental pollution. Treatments are lengthy with low adherence rates. Given the historical use of plants in disease treatment, natural products, such as essential oils (EOs), have been studied and developed for fungal infection treatment. Therefore, the aim of this study was to conduct a systematic literature review on Origanum species commercialized in Brazil: O. compactum, O. minutiflorum, O. syriacum, and O. vulgare, focusing on the chemical composition of their oils and their antifungal activity. A systematic literature review was conducted following Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines, using ScienceDirect, SciELO, PubMed, Scopus, and Web of Science databases. O. vulgare presented the largest number of articles, and O. compactum showed the best results in terms of minimum inhibitory concentration (MIC) and against the evaluated fungal species. Candida spp., Aspergillus spp., and Penicillium spp. were the most studied fungi. Carvacrol, thymol, p-cymene, o-cymene, and γ-terpinene are key constituents linked to their antifungal effects. The findings of this review highlight the chemical diversity of the studied genera and emphasize the potential of Origanum spp. EOs as antifungal agents against a variety of fungi.