Despite their clinical success, chimeric antigen receptor (CAR)-T cell therapies for B cell malignancies are limited by lengthy, costly and labor-intensive ex vivo manufacturing procedures that lead to cell products with heterogeneous composition. In this talk, I will describe several biomaterials technologies that streamline CAR T cell manufacturing and reduce processing times to a single day. Biomaterials provide the appropriate interface and signaling for T cell activation, viral vector-mediated gene transfer, expansion and release of functional CAR-T cells. Further, in vivo-generated CAR-T cells enter the bloodstream and control distal tumor growth in mouse models of lymphoma, lung, ovarian and orthotopic pancreatic cancer. Biomaterial cell factories could transform CAR-T cell therapy by fast-tracking manufacture and reduce the complexity and resources needed for provision of this type of therapy.