Electrochemiluminescence (ECL) is widely employed formedical diagnosisand imaging. Despite its remarkable analytical performances, the techniqueremains intrinsically limited by the essential need for an externalpower supply and electrical wires for electrode connections. Here,we report an electrically autonomous solution leading to a paradigmchange by designing a fully integrated all-optical wireless monolithicphotoelectrochemical device based on a nanostructured Si photovoltaicjunction modified with catalytic coatings. Under illumination withlight ranging from visible to near-infrared, photogenerated holesinduce the oxidation of the ECL reagents and thus the emission ofvisible ECL photons. The blue ECL emission is easily viewed with nakedeyes and recorded with a smartphone. A new light emission scheme isthus introduced where the ECL emission energy (2.82 eV) is higherthan the excitation energy (1.18 eV) via an intermediate electrochemicalprocess. In addition, the mapping of the photoelectrochemical activityby optical microscopy reveals the minority carrier interfacial transfermechanism at the nanoscale. This breakthrough provides an all-opticalstrategy for generalizing ECL without the need for electrochemicalsetups, electrodes, wiring constraints, and specific electrochemicalknowledge. This simplest ECL configuration reported so far opens newopportunities to develop imaging and wireless bioanalytical systemssuch as portable point-of-care sensing devices.