In this work, four new cyclodepsipeptides, fusarihexins C-E (<b>1</b>-<b>3</b>) and enniatin Q (<b>4</b>), four new cyclopentane derivatives, fusarilins A-D (<b>5</b>-<b>8</b>), together with eight known compounds (<b>9</b>-<b>16</b>), were isolated from cultures of the endophytic fungus <i>Fusarium</i> sp. The structures of the isolated compounds were elucidated by analysis of HRMS and NMR spectroscopic data. The absolute configurations were determined using Marfey's method, a modified Mosher's method, single-crystal X-ray diffraction analysis, and ECD analysis. The antitumor activities of the isolated compounds in vitro were evaluated. Cyclodepsipeptides displayed cytotoxicities against the Huh-7, MRMT-1, and HepG-2 cell lines. Compounds <b>4</b>, <b>9</b>, <b>10</b>, and <b>12</b> with IC<sub>50</sub> values of 1.0-9.1 μM exhibited the most potent cytotoxicities against the three cell lines as compared to the positive control-5-fluorouracil. Compounds <b>1</b>-<b>3</b> and <b>11</b> exhibited moderate cytotoxic activities (IC<sub>50</sub> values of 10.7-20.1 μM).