One new cyclohexenone derivative (1), and two undescribed drimane sesquiterpenes (2 and 3), together with another seven known drimane sesquiterpenes were isolated from a seagrass-derived fungus Aspergillus insuetus SYSU6925. Structures of these metabolites were elucidated by comprehensive spectroscopic analysis, including comprehensive NMR analysis, mass spectrometry, and ECD calculations. Compounds 1-3, 5 and 7 displayed weak to moderated antifungal activities towards four phytopathogenic fungi, with Minimum inhibition concentration (MIC) values ranging from 50 to 200 µg/mL. The compound 1, a rare cyclohexenone derivative with n-propyl group exhibited more potent inhibitory activities (MIC, 50 µg/mL) against F. oxysporum than positive control (Triadimefon). Compounds 2 and 3 also exhibit potent anti-inflammatory activities by inhibiting the production of nitric oxide (NO) in RAW264.7 cells with IC50 values of 21.5±1.1 and 32.6±1.16 µM, respectively.