Curcumin is known to suppress the progression of colorectal cancer by inhibiting cancer cell proliferation. In this study, we explored the role of ferroptosis in the antiproliferative properties of curcumin. The effect of curcumin on ferroptosis In Vitro was evaluated in HCT-8 cells. Ferroptosis was first blocked by ferrostatin-1 (Fer-1) and the antiproliferative effect of curcumin was evaluated by determining the levels of ferroptotic markers, including glutathione (GSH), SLC7A11, GPX4, iron, malondialdehyde (MDA), and reactive oxygen species (ROS). An agonist and an inhibitor of PI3K were also used to verify the signaling pathway involved in the antiproliferative effects. Curcumin repressed HCT-8 cell proliferation in a dose-dependent manner. Treating HCT-8 cells with curcumin significantly downregulated GSH, SLC7A11, and GPX4, while significantly increasing levels of iron, MDA, and ROS. In addition, curcumin promoted ferroptosis and reduced proliferation of HCT-8 cells by suppressing the PI3K/Akt/mTOR pathway, and these effects were antagonized by Fer-1. The effects of curcumin were antagonized by a PI3K agonist and reinforced by a PI3K inhibitor. Curcumin triggers ferroptosis and suppresses proliferation of colorectal cancer cells by inhibiting the PI3K/Akt/mTOR signaling pathway. These results indicate its potential as a treatment against colorectal cancer.