Background: Endophytic fungi are of a growing interest as prominent sources of structurally unique bioactive natural products. Objective: This study aims to isolate and characterize bio-metabolites from the endophytic fungus Fusarium sp. isolated from Mentha longifolia L. roots as well as to assess the antimicrobial and cytotoxic potential of these metabolites. Materials and Methods: The endophytic fungi Fusarium sp. was cultured on a rice medium. The rice cultures' ethyl acetate extract was separated using various chromatographic techniques (SiO2, RP-18, and sephadex LH-20) to afford four metabolites. Their structural characterization was achieved by various spectroscopic analyses, as well as comparing with the published data. Results: A new ergosterol derivative namely, fusaristerol A (22E,24R-5β,8β-epidioxyergosta-22-en-3β-yl decanoate) (1), along with ergosta-7,22-diene-3β,5α,6β-triol (2), ergosta-5,7,22-triene-3β-ol (3), and (22E,24R)-ergosta-7,22-dien-3β-ol (4), was separated. Fusaristerol A (1) possessed a significant antifungal activity toward Candida albicans with minimum inhibitory concentration (MIC) value of 8.3 μg/disc compared to clotrimazole (MIC 5.1 μg/disc). Moreover, it displayed a potent cytotoxic potential toward HCT-116 cell line with an half maximal inhibitory concentration (IC50) value of 0.21 μM, compared to doxorubicin (IC50 0.06 μM). Conclusion: This is the first report for separation of a 5,8-epidioxy ergostane derivative from Fusarium sp. Fusaristerol A may provide a new promising candidate for the development of a potential anti-candida and cytotoxic agent.