Despite its innovative approach, Jessup’s bold proposal for transnational law has gotten little attention within the realm of international law. The intrinsic state-centric perspective of international law appears to contradict the distinctive features of transnational law, which focus on the role of non-state actors in international affairs. However, the state-centric international society has been facing considerable challenges due to its rigidity, necessitating a comprehensive reassessment of the capacities of both the States and international law to solve transnational issues. The concerns raised are hotly debated within the discourse on transnational law. Transnational law is envisioned as a comprehensive legal framework that integrates domestic law, public international law, private international law, and other rules. The need to reconsider the role of international law in the context of transnational law is becoming apparent because the nature of post-national law is highlighted as a unique characteristic of transnational law. While non-state actors’ private regulatory mechanisms play a pivotal role in the establishment and maintenance of transnational law or transnational legal orders, States and international law continue to play crucial roles. States and international law, in particular, are exclusively positioned to govern certain transnational activities that could not be subject to private regulatory mechanisms, such as the prohibition of the use of force and international criminal justice. Furthermore, international law serves as a steering mechanism, settling problems between the diverse legal systems that comprise transnational law. Transnational law and transnational legal orders necessitate a coherent integration of private regulatory mechanisms and public normative systems. In this context, international law is pivotal, providing background norms that facilitate the coordination of various legal systems under the umbrella of transnational law. It is critical to recognize that transnational law operates as a legal system that relies on the support of international law, rather than sidelining it.