Here, a mechanoluminescence-assisted double cantilever beam (DCB) test was proposed and its effectiveness was demonstrated. Based on mechanoluminescence, a crack tip was clearly distinguished and successfully tracked during crack propagation and delamination in the DCB test, which helped overcome the difficulty associated with the conventional DCB test. The crack length could be easily determined and used to evaluate the fracture toughness. In addition, mechanoluminescence sensing using the top image of the DCB specimen provided valuable information on the fracture and adhesive frontline to determine the distribution of fracture toughness and adhesive strength under the surface treatment and adhesion curing conditions in the DCB test.