Modern Ukrainian constitutionalism is a complex political and legal system in the functioning of which the parliament plays an important role. Considering that constitutionalism is a goal of constitutional-legal transformations that have been taking place in Ukraine since its rebirth as a sovereign and independent state in 1991, the study of its formation does not lose its signifi cance. At the same time, within the availability of serious conceptual developments, there is a lack of scientifi c and practical researches on the role and importance of the parliamentarism institute in the constitutionalism system. Moreover, this problem is actualized by the necessity of the further development of the Ukrainian Parliament. Thus it is necessary to continue the parliamentary reform to increase the institutional capacity of the Verkhovna Rada of Ukraine, improve the parliamentary control and legislative process that aims to establish modern Ukrainian constitutionalism. All of this constitutes a problem, solving of which predetermines the necessity of appropriate scientifi c researches and forms the purpose of the article. The purpose of the article is to defi ne the doctrinal concept of the role (functions) and signifi cance of the Parliament in the system of constitutionalism and solve the current issues of the constitutional and legal practice of the functioning of the domestic Parliament in the context of the establishment and development of modern Ukrainian constitutionalism. As a result of the scientifi c and practical study performed, the conclusion has been made that the Parliament as the main institute of modern parliamentarism has the signifi cance of the universal phenomenon of the system of modern Ukrainian constitutionalism. This has been predetermined by the fact that the Verkhovna Rada of Ukraine in the constitutionalism system performs the following functions: forms the normative basis of the modern constitutionalism through the execution of its powers, i.e. bringing changes to the Constitution of Ukraine and the adoption of laws, which are necessary to implement the principles and mechanisms of functioning of the constitutionalism system in the constitutional-legal reality; it also promotes the establishment of the constitutional legality and the constitutional legal order, which are the constituent elements of the constitutionalism system, by exercising its control powers (exercising parliamentary control); it protects the rights and freedoms of a man and citizen through the functioning of the Ukrainian Parliament Commissioner for Human Rights and thereby contributes to the establishment of the constitutional legal human freedom, i.e. the goal of the modern Ukrainian constitutionalism. Key words: parliament, parliamentarism, modern Ukrainian constitutionalism, law-making, parliamentary control.