Electrochemiluminescence (ECL) describes the generation of luminescent light in solution, initiated by electrochemical reactions. ECL serves as an important tool in analytical chemistry, especially in clinical immunosensing applications. Additionally, ECL is being explored for innovative biological imaging techniques and utilized in fundamental studies of reactions at mesoscopic concentrations and even at the single-particle level. Numerical simulation tools, such as finite element methods (e.g., COMSOL Multiphysics), are commonly employed in ECL research. These tools are highly effective for elucidating the underlying physical chemistry of ECL processes, as they incorporate the complex interactions between electrochemical and chemical reactions, mass transport of reactants, and the lifetimes of luminescent ECL radicals. Through simulations, researchers can obtain cyclic voltammograms, light intensity profiles, and spatial distributions of the molecules involved.