Water security is one of the significant challenges that many countries worldwide face. In the context of population growth, climate change, and environmental pollution today, the issue of water security is more urgent than ever for countries. In recent years, water security for countries in the Mekong River Basin has been facing great challenges, potentially leading to disputes and conflicts between the countries involved. From a regional perspective, the article clarifies the relationship between the lower Mekong countries in protecting water security and especially Vietnam's role in that relationship to clearly see the achievements that countries have achieved, as well as the challenges posed in the relationship on water security. From there, some policy suggestions are given to promote effective relations between countries in stabilizing the water security of the Mekong River, especially for Vietnam, a country located at the bottom of the Mekong River.   Received: 21 January 2023 / Accepted: 16 April 2023 / Published: 5 May 2023