Here, by using the MC38 mouse colon cancer model frequently employed to study the antitumor T cell response, as well as anti‐PD‐1/PD‐L1 immunotherapy, we revealed the helper role of NK cells in the antitumor T cell response by showing that the T‐bet/Eomes‐IFN‐γ axis in NK cells is essential for CD8+ T cell‐dependent tumor control and that T‐bet‐dependent NK cell effector functions are required for an optimal response to anti‐PD‐L1 immunotherapy. The gene discussed is EOMES; the disease is malignant colon neoplasm.