Marine-derived fungi have emerged as valuable sources of pharmacologically active lead compounds with potent antimicrobial properties. In this study, six previously undescribed bisabolane-type sesquiterpenes (1-6), including a rare 5,6-dihydrobenzoic acid derivative of the bisabolene skeleton (1), along with 18 known compounds (7-24), were isolated from the ethyl acetate extract of the marine fungus Aspergillus sp. WHUF04-170. The chemical structures of these metabolites were elucidated through comprehensive spectroscopic analysis, including UV, IR, HRESIMS, and 1D/2D NMR spectroscopy. The antimicrobial potential of the isolated compounds was subsequently evaluated in vitro. Compounds 9, 10, 15, 16, and 19 exhibited moderate antibacterial activity against both the standard Helicobacter pylori strain G27 and the multidrug-resistant strain HP159, with minimal inhibitory concentration values ranging from 16 to 32 μg/mL. Notably, synergistic antimicrobial assays revealed that compounds 1 and 15 enhanced the activity of amphotericin B against Candida albicans strains, including both standard reference strains (SC5314 and ATCC 10231) and drug-resistant clinical isolates (C5 and C3). Collectively, these findings expand the structural diversity of bisabolane-type sesquiterpenes and highlight their dual antimicrobial potential, offering promising leads for the development of combination therapies against resistant pathogens.