Adoptive T-cell therapy against solid tumours is limited by the apoptosis resistance mechanisms of tumour cells and by the extracellular, immunosuppressive tumour microenvironment. Here we report a temperature-sensitive genome-editing nanodevice that can deliver a Cas9 editor with an external trigger which can be used to edit the genome of tumour cells to reduce resistance to apoptosis and modulate the tumour microenvironment via a mild heating trigger. After local or systemic delivery of Cas9, mild heating is induced by non-invasive near-infrared (NIR) light or focused ultrasound (FUS) to activate Cas9, which initiates simultaneous genome editing of HSP70 (HSPA1A) and BAG3 in tumour cells. This disrupts the apoptotic resistance machinery of the tumour cells against adoptive T cells. At the same time, an NIR- or FUS-induced mild thermal effect reshapes the extracellular tumour microenvironment by disrupting the physical barriers and immune suppression. This facilitates the infiltration of adoptive T cells and enhances their therapeutic activity. Mild thermal Cas9 delivery is demonstrated in different murine tumour models which mimic a range of clinical indications, including a tumour model based on humanized patient-derived xenografts. As a result, the non-invasive thermal delivery of Cas9 significantly enhances the therapeutic efficacies of tumour-infiltrating lymphocytes and chimeric antigen receptor T and shows potential for clinical application.