Introduction: In an on-going research, the endophyte Aspergillus sp. HAB10R12 have been selected for detailed chemical investigation after its crude ethyl acetate extract showed promising anticancer properties with high selectivity. Methods: The former was determined on two cancer cell lines namely, HCT116 and MCF-7 (IC50 = 0.05 and 0.04 μg/mL, respectively) and one non-tumor cell line HeLa (IC50 = 10.5 μg/mL). Results: The result indicates the secondary metabolites produced by the fungus are 200 folds more selective towards cancer cells over normal cells, calling for an immediate detailed investigation of their composition. Preliminary chemical analysis of the crude extract using LC-MS, NMR and UHPLC-UV showed the presence of an uncommon group of diterpene pyrones (NF00659 A1, B1 and A3), previously isolated once with only partial characterization reported. Consequently, large scale isolation of secondary metabolites was carried out and led to the identification of four of the previously isolated diterpene pyrones. Conclusion: The isolation, characterization, relative stereochemistry analysis, and a plausible biosynthesis of the diterpene pyrone compounds is presented herein.