Georg Schwarzenberger’s oeuvre has remained significantly underexplored in International Relations literature despite his status as one of the most important thinkers in International Relations and international law of the twentieth century. Ahead of their time, his works reveal a picture of law that transcends academic boundaries and challenges the traditional portrayal of both realist theory and international law. Through a detailed examination of the works of this theorist, this article offers an analysis of the fundamental aspects of his theory of International Relations and international law. It explores the elements at the heart of Schwarzenberger’s theory of International Relations, which, though examined infrequently and practically forgotten, retain their relevance in today’s international society. Through this exploration of Schwarzenberger’s works, this article argues that his theory of International Relations provides a powerful commentary on the fundamental structure, nature and problems of international law. It points to and reveals issues that have remained at the heart of international law until today, offering a sophisticated and self-conscious interrogation of the relationship between law, power and politics. In doing this, this article challenges our understanding of realism as a theory that is unable to account for international law and highlights Schwarzenberger’s continued relevance today.