This animal proof-of-concept study describes an engineered nanoparticle–cell interface (EMPOWER) enabling wireless regulation of transgene expression using a 1-kHz magnetic field. Chitosan-coated multiferroic nanoparticles reportedly generate intracellular ROS that activates KEAP1/NRF2 biosensors connected to ROS-responsive promoters. In a mouse model of type 1 diabetes, implanted engineered cells expressing an EMPOWER-controlled insulin system reportedly normalized blood glucose in response to a weak magnetic field.