The waters of South and Southeast Asia have historically been a prolific breeding ground for a variety of organized crimes that fall under the umbrella of maritime domains. In the contemporary geopolitical landscape, the menace of terrorism has escalated, exhibiting a marked tendency towards global proliferation. This phenomenon is compounded by the acquisition of advanced and efficient instruments by terrorist groups, thereby expanding the scope and diversifying the nature of terrorism. Notably, maritime spaces have become a focal point of concern, as terrorist activities have permeated these domains, underscoring the need for comprehensive and proactive responses to address this global threat. Maritime terrorism, particularly in regions where other forms of maritime crime are prevalent, constitutes a grave threat to peace and security at sea due to the emergence of criminal linkages among perpetrators. The organized nature of these crimes necessitates collective efforts to combat them effectively. In this regard, the role of regional international organizations in countering maritime terrorism is indisputable. This article employs a descriptive-analytical approach to evaluate the performance of selected organizations active in South and Southeast Asia in combating maritime terrorism. The article assesses the strengths, weaknesses, and challenges of these organizations. The findings indicate that, while the activities of these organizations are necessary, they remain inadequate. The most significant challenge in this domain is the absence of collective regional strategies.