The structural phase of micelles plays an important role in controlling the micellar performance. Despite the great developments of some advanced characterization techniques, it remains challenging to achieve fast and sensitive determination of micellar transitions in solution. Herein, a novel indicator system for micellar transitions was developed based on the micelle-mediated peroxyoxalate chemiluminescence that showed a sensitive response toward the changes of micellar morphologies. A peroxyoxalate derivative and a fluorophore were first coassembled into the hydrophobic cavities of micelles of the typical cationic surfactant cetyltrimethylammonium bromide (CTAB). A strong and rapidly falling chemiluminescence response was exhibited in spherical micelles as a result of the loose arrangement of CTAB molecules. By contrast, rodlike or wormlike micelles transformed from spherical micelles could induce a compact arrangement of CTAB molecules, leading to a weak chemiluminescence emission with a slow decay rate. The practicability and universality of the chemiluminescent indicator were demonstrated by determining the micellar transitions in a variety of surfactant solutions (ionic, nonionic, and polymeric). These findings open attractive perspectives for the practice of chemiluminescence technique in micelle characterization.