Considering that the Islamic Republic of Iran is a member of both organizations, the study also addresses Iran’s position within the international regime for the protection of the marine and aviation environment and the interaction between its international obligations and the requirements of national sovereignty. The research employs a descriptive–analytical method and is based on library research, utilizing legal sources, international documents, and relevant conventions. The examination of the competences of IMO and ICAO demonstrates that these organizations play a significant role in improving safety and reducing environmental pollution through the development of technical standards and regulations in maritime and air transportation. The IMO seeks to ensure safe shipping and prevent marine pollution, while the ICAO based on the provisions of the Chicago Convention and the principles of international air law, including the principle of state sovereignty over airspace has developed frameworks for international cooperation in environmental protection. As a member of these organizations, the Islamic Republic of Iran has also taken steps toward aligning its domestic regulations with international standards and implementing environmental requirements. In international environmental law, the principle of state sovereignty is recognized alongside states’ responsibility to prevent environmental harm to other countries. Accordingly, the competences of the IMO and ICAO should not be viewed as conflicting with state sovereignty but rather as part of a framework for international cooperation aimed at environmental protection. For countries such as the Islamic Republic of Iran, this requires strengthening domestic legal and institutional mechanisms to effectively implement international standards.