Cancer is a growing global health concern, and photodynamic therapy (PDT) has emerged as a promising technology with minimal side effects for cancer treatment. Miniaturized PDT devices that offer a flexible and convenient strategy for the low-dose delivery of light or drugs are needed to replace invasive optical fibers. Here, we present a self-powered, wireless, and detachable drug/light injector that conforms to the properties of metronomic PDT for cancer treatment. The device comprises a semi-invasive pedestal with a micro light emitting diode (& mu;-LED) and a syringe needle, and a detachable actuator that contains a drug reservoir, a thermally-driven pump, and a wireless control circuit. The two parts are magnetically attracted to each other, and the detachable actuator can be conveniently replaced or refilled with drugs. The device can be wirelessly controlled to deliver on-demand dosages of drugs and light into the tumor under the skin. Additionally, we further demonstrate that the device can in principle be partially self-powered using body motion energy upon connection to different piezoelectric nanogenerators. In-vitro and in-vivo experiments on mice have demonstrated the feasibility of the device's therapeutic regimen for implementing metronomic PDT. The average volume of tumors in the treatment group was reduced by 57.4 % compared to the control group. This device has potential applications in future clinical cancer treatment and can expand the scope of self-powered systems for biomedical engineering.