A stability-indicating method (SIM) stipulates the testing of the drug product and drug substances under the stressed conditions that will imply a clear notion about the stress conditions that would affect the drug in its finished dosage form. Furthermore, manufactures can clearly define the state at which the drug is unstable and present its storage conditions. The present article deals with the stability testing and degradation kinetic studies of desloratadine (DL). The method of analysis was UV visible spectroscopy, which is a most convenient and reliable method for the analyst. A method was developed and validated according to the ICH Q2 guidelines along with the amendment in 2018 (ICH Q14). The study denotes that the drug is extremely unstable in the presence of dry heat and then follows the oxidative and basic degradations. The acidic, neutral, and photolysis did not show notable degradations. The chemical kinetic studies were carried out to more clearly understand the mechanism of degradation and to present the order of reaction, rate of reaction, and reaction half-time. The application of a spectrophotometric method in the development of a SIM and study of degradation kinetics is much handier and cost-effective.