The integration of large-scale transnational electricity networks is a strategic imperative that offers multifaceted benefits, including economic, environmental, social, and technological advancements. This paper reviews information exchange mechanisms’ development and current state within some mature cross-border interconnected power systems. The information exchange mechanisms are continuously revised to improve the stability and reliability of the power supply. This study underscores the importance of cross-border grid information sharing, highlighting the differences in mechanisms across various regions, particularly focusing on European, Nordic, and North American grids. The analysis delves into the operational and strategic aspects of these mechanisms, including the role of entities like the North American Electric Reliability Corporation and the European Network of Transmission System Operators for Electricity. The paper clarifies the main differences in grid information exchange mechanisms across various regions and endeavors to elevate the holistic insight of the essential information for the security operation of large interconnected electricity networks.