Electrochemiluminescence (ECL) is a well-established analytical method, which is evolving into a powerful optical microscopy technique. The orthogonality of the electrochemical trigger and optical readout distinguishes it from classic microscopy since it does not require any photo-excitation. ECL was used to dynamically image local changes in (electro)chemical activity and a wide range of objects, including those with electrocatalytic, insulating, or biological properties. By playing with the electrogenerated light and the surrounding darkness, various approaches have been developed to image biological entities such as cells, bacteria, mitochondria, spheroids, tissue sections, etc. and cell-like microreactors (e.g., liposomes, droplets, etc.).