Two new naphthalenones, corynenones A and B (1 and 2), and one new depsidone, corynesidone E (3), together with one known depsidone, corynesidone A (4) and two known diphenyl ethers, corynethers A (5) and B (6), were isolated from the sponge-derived fungus Corynespora cassiicola XS-20090I7. Their structures including absolute configurations were determined by spectroscopic data and electronic circular dichroism (ECD) spectra. Compounds 4 and 5 showed cytotoxicity against human promyelocytic leukemia HL-60 and human cervical carcinoma HeLa cell lines.