The development of globalization and technological advances has given birth to various new forms of crime that are transnational in nature and have the potential to threaten the interests of the international community. This condition has given rise to a debate about the limits of criminalization of an act as an international crime based on international law. This study aims to analyze the limits of criminalization of new international crimes based on the principles of international law and identify the legal parameters that must be met in order for an act to be categorized as an international crime. This study uses normative legal research methods with a statutory approach, a conceptual approach, and a case approach. Legal materials are obtained through literature studies which include international regulations, conventions, the 1998 Rome Statute, books, scientific journals, and other relevant legal documents. The results of the study show that an act cannot be categorized as an international crime just because it has a broad impact or is cross-country. Criminalization must be based on the principle of legality (nullum crimen sine lege), recognition through international treaties or customary international law, protection of the fundamental interests of the international community, and the existence of individual criminal responsibility. New forms of crime, such as ecocide, cybercrime, and the abuse of artificial intelligence, still face juridical and political challenges to gain recognition as international crimes. Therefore, it is necessary to develop international criminal law that is adaptive, but still guided by the principles of legal certainty, respect for state sovereignty, and the protection of human rights.