This study investigated the efficacy of the One Strain Multiple Compounds (OSMAC) strategy in enhancing the anti-cancer potential of metabolites derived from the marine fungus Aspergillus sp. Y-WS27. Twenty-five culture conditions were employed to assess the inhibitory effects of crude extracts on cancer cell proliferation. Among them, the extract obtained from rice solid culture (R-0) demonstrated significantly enhanced inhibitory activity, as revealed by base peak chromatograms (BPC). The metabolite profile of R-0 showed a marked increase in the diversity and abundance of secondary metabolites compared to the control group (P-0). Ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS), along with ACD/MS Structure ID Suite, identified eight distinct compounds (1-8). These included butyrolactones, terretonins, and monacolin derivatives. Further purification yielded 17 compounds (1-17), with compounds 7 and 9 exhibiting significant anti-proliferative effects against MCF-7, A549, and HeLa cancer cells (IC values ranging from 9.88 to 30.28 μg/mL). Compound 7 displayed superior efficacy with IC values of 12.12, 10.21, and 9.88 μg/mL, respectively, while compound 9 showed moderate activity with reduced cytotoxicity to normal HK-2 cells. These findings demonstrated the utility of the OSMAC strategy in modulating secondary metabolite production and revealing previously undetected compounds. This research provided a robust framework for the discovery of novel natural products with therapeutic potential against cancer.