Updated project metadata. Cancer cells frequently alter their lipids to grow and adapt to their environment1–3. Despite the critical functions of lipid metabolism in membrane physiology, signaling, and energy production, how specific lipids contribute to tumorigenesis is incompletely understood. Here, using functional genomics and lipidomic approaches, we identified de novo sphingolipid synthesis as an essential pathway for cancer immune evasion. Synthesis of sphingolipids is surprisingly dispensable for cancer cell proliferation in culture or in immunodeficient mice but required for tumor growth in multiple syngeneic models. Blocking sphingolipid production in cancer cells enhances the anti-proliferative effects of natural killer (NK) and CD8+ T cells partly via interferon gamma (IFNg) signaling. Mechanistically, depletion of glycosphingolipids increases surface levels of IFNg receptor subunit 1 (Ifngr1), mediating IFNg-induced growth arrest and proinflammatory signaling. Finally, pharmacological inhibition of glycosphingolipid synthesis synergizes with checkpoint blockade therapy to enhance anti-tumor immune response. Altogether, our work identifies glycosphingolipids as necessary and limiting metabolites for cancer immune evasion.