The issue of divine decree and predestination is one of the fundamental subjects of Islamic theology that was also reflected in the doctrinal and political disputes of the early Islamic period. One noteworthy example in this regard is Muʿāwiya ibn Abī Sufyān’s invocation of divine decree and predestination to explain or justify certain actions and political events during his rule. Adopting a descriptive-analytical and critical approach, the present study examines the foundations and function of this invocation and seeks to assess its conformity with the teachings of the Qurʾan and Islamic traditions. To this end, it first explains the concept of divine decree and predestination and its relationship to human will and free choice; it then examines the principal instances in which the Umayyads (Muʿāwiya and others) invoked divine predestination in historical and ḥadīth sources and compares them with Qurʾanic verses indicating human moral responsibility, free choice, and accountability. The findings demonstrate a fundamental distinction between “acceptance of divine decree and predestination” as a doctrinal principle and “the use of divine decree and predestination to absolve the human agent of responsibility.” Accordingly, invoking divine decree and predestination to justify voluntary acts and to absolve an individual of moral and political responsibility is incompatible with the teachings of the Qurʾan and Islamic traditions. On this basis, Muʿāwiya’s predestinarian argument may be evaluated and criticized as an instrument for political legitimation and justification.