Lenvatinib, a tyrosine kinase inhibitor, has been approved for the treatment of several cancers. However, its regulatory activity and related mechanisms on T cell antitumour immunity need to be further investigated. The antitumour activity of lenvatinib in immunocompetent and immunodeficient mice was compared to determine the role of T cell immunity. The antitumour activity of T cells was analysed by cytokine production and adoptive T cell therapy. The immunosuppressive effects of MDSCs on T cells were determined by detecting cytokine production in T cells after being cocultured with MDSCs. The adjuvant immunotherapy effect of lenvatinib was determined by combination therapy with CAR-T cells targeted carbonic anhydrase IX (CAIX) in a murine renal cancer model. The antitumour activity of lenvatinib was greater in immunocompetent mice than in immunodeficient mice and was attenuated by CD8+T cell depletion. Lenvatinib increased proliferation, tumour infiltration and antitumour activity of T cells. Importantly, adoptive transfer of lenvatinib-treated T cells showed a long-term antitumour response in vivo. Mechanistically, lenvatinib upregulated T cell-related chemokines (CXCL10 and CCL8) in tumours and decreased the frequency and immunosuppressive activity of MDSCs. Furthermore, lenvatinib enhanced the efficacy of CAR-T cells in a murine renal cancer model. Our study revealed novel antitumour mechanisms of lenvatinib by enhancing T cell-mediated antitumour immunity. These findings are of great significance for guiding the clinical use of lenvatinib and provide a good candidate for future combination therapy with T-cell therapies or other immunotherapies. [Display omitted] • Lenvatinib increased T cell infiltration into tumours by upregulating the expression of CXCL10 and CCL8. • Lenvatinib enhanced the antitumour activities of T cells by decreasing frequency and immunosuppressive activity of MDSCs. • Adoptive transfer of lenvatinib-experienced T cells showed a long-term antitumour response in vivo. • Lenvatinib enhanced the antitumour activity of combination treatment with CAR-T cells in a murine renal cancer model. [ABSTRACT FROM AUTHOR]