Summary There have been reports of haematological cancer patients achieving spontaneous remission after being infected with the influenza A or SARS‐COV‐2 virus. Here, we present the first case of long‐term complete remission (CR) induced by influenza A (IAV, H1N1 subtype) in a refractory AML patient and have functionally validated this finding in two different animal disease models. We observed a significant increase in the proportion of helper T cells in the patient after IAV infection. The levels of cytokines, including IL‐2, IL‐4, IL‐6, IL‐10, IL‐17A, IFN‐γ and TNF‐α, were higher in IAV‐infected patients compared with control groups. These findings indicate that the anti‐tumour effects induced by IAV are closely related to the modification of the immune response. Our study provides new evidence of the anti‐tumour effects of IAV from a clinical practice perspective.