icFSP1, an inhibitor of ferroptosis suppressor protein 1 (FSP1), promotes condensation and phase separation of FSP1 in cellular environments at 2.5 µM concentration but does not affect FSP1's enzymatic function in cell-free assessments (IC50 = > 30 µM). This compound selectively induces ferroptosis in HT-1080 fibrosarcoma cells in a dose-dependent manner. Furthermore, in vivo studies show that icFSP1 administered at 50 mg/kg significantly reduces both the volume and weight of tumors in a B16/F10 murine melanoma model utilizing human FSP1-overexpressing, Gpx4-/-Fsp1-/- B16/F10 cells.