Supramolecular polymerization has been a fascinating frontier of supramolecular chemistry in fabricating well-defined hierarchical nanostructures. However, the reverse process, that is, supramolecular depolymerization in which superstructures disassemble into subunits, is far less explored. In particular, the mechanism and kinetics of supramolecular depolymerization have not yet been reported. In this work, we discovered a thermal-induced supramolecular depolymerization of nanowires formed by supramolecular step-growth polymerization of preassembled micelles. With increasing temperature, the intermicelle interaction between the micellar subunits is broken, resulting in depolymerization of the nanowires into micellar subunits. Accompanying the supramolecular depolymerization, chain transfer between the subunits occurs. A theoretical model was proposed to reveal the mechanism and kinetics of the supramolecular depolymerization. It was found that the depolymerization behavior obeys the rules of random depolymerization. The present work could provide useful information for understanding the underlying principles of supramolecular degradation. In addition, the temperature-induced supramolecular depolymerization of hierarchical nanostructures may find potential applications in biomedical fields.