This paper explores the critical interplay between maritime security and the Blue Economy in Southeast Asia, emphasising that regional economic aspirations are intertwined with geopolitical realities. While ASEAN has made significant strides in articulating a collective vision for the Blue Economy—most notably through the 2021 Leaders’ Declaration and the 2023 ASEAN Blue Economy Framework—these initiatives largely sidestep the region’s complex security challenges. The authors argue that maritime disputes, criminal activities, and great power competition, particularly in the South China Sea, pose significant threats to Blue Economy outcomes. These tensions undermine regional cooperation, deter investment, and hinder sustainable development. Conversely, the paper posits that advancing Blue Economy initiatives could foster improved maritime security, leveraging the symbiotic relation between development and stability. Three key sectors are examined for their impact: marine spatial planning, maritime connectivity (including port development and shipbuilding), and monitoring, control, and surveillance (MCS). The paper highlights the need for integrated, cross-border marine spatial planning, equitable port development, and regional MCS frameworks to support sustainable fisheries and deter illegal activities. Policy recommendations include establishing ASEAN task forces for marine spatial planning and port security, investing in regional shipbuilding, and leveraging existing maritime domain awareness infrastructure for MCS. The authors advocate for a shift in ASEAN’s approach—from avoiding security issues to actively engaging with them through economic cooperation. The paper calls for ASEAN to embrace the Blue Economy not just as a growth strategy, but as a pathway to regional peace, stability, and sustainable ocean governance.<p></p>