Enzyme-based biofuel cells implanted into living lobsters or designed as fluidic systems mimicking human blood circulation were used for powering electronic devices. Two lobsters with implanted biofuel cells connected in series were able to generate open circuit voltage (V_oc) up to 1.2 V and an electrical watch, selected as a model electronic device, was activated by the power extracted from the “living battery”. The fluidic system composed of five cells filled with human serum solution connected in series generated V_oc of ca. 3 V and was able to power a pacemaker. Sustainable operation of the pacemaker was achieved with the system closely mimicking human physiological conditions characteristic of normal and pathophysiological glucose concentrations with the fluidic rate typical for a blood circulation upon resting or performing physical exercises. While the “cyborg” lobsters demonstrate a model system with future possible military, homeland security and environmental monitoring applications, the system activating a pacemaker presents practicality for biomedical applications. The first demonstration of the pacemaker activated by the physiologically produced electrical energy shows promise for future electronic implantable medical devices powered by electricity harvested from the human body.