We report a particulate cell delivery platform, toroidal spiral particles (TSPs), for continuous cell activation, expansion, and local sustained release. Biocompatible TSPs, generated by a self-assembly process of polymeric droplet sedimentation in an aqueous solution and subsequent polymer solidification, possess many engineering design flexibilities to manipulate the microenvironment of the cells to control cell proliferation, migration, and release kinetics. These millimeter-size particles with desired mechanical and physicochemical properties may be potentially used for adoptive cellular therapy (ACT) delivery by a minimally invasive procedure to the tumor mass.