In many deltaic regions of the Global South, climate change is driving fundamental shifts in human land-use practices. These transformations exert significant pressure on livelihood security and public health, particularly in deltas heavily reliant on land and water for sustenance. Vietnam’s Mekong Delta exemplifies this dynamic that rising sea levels, salinization, and altered Mekong River flows are compelling agricultural production systems to adapt, thereby undermining rural livelihoods, threatening food security, and challenging traditional land governance mechanisms. To interpret and evaluate these changes, this chapter applies the theoretical framework of “adaptive governance”, focusing on institutional flexibility, polycentric coordination, and community participation within Vietnam’s land and climate policies. The analysis is situated within the context of the Land Law 2024 and the National Climate Change Strategy 2022, highlighting prominent limitations such as fragmented management authority, ineffective intersectoral coordination, and limited integration of local knowledge. The study further extends its scope through comparative analysis with other vulnerable deltas, including the Nile, Brahmaputra, and Mississippi, to identify transferable principles for other developing nations in the Global South. The findings underscore that an effective legal framework for climate change response must ensure three key elements: (i) flexibility in institutional and land-use planning frameworks, (ii) active community engagement, and (iii) intersectoral coordination. Crucially, integrating indigenous knowledge with modern science enhances resilience while safeguarding public health, food security, and sustainable development. Through this experience, Vietnam not only draws valuable lessons from international models but also contributes to constructing adaptive governance frameworks for nations severely impacted by climate change.