Wasting, also called as acute malnutrition, is diagnosed in children 6 to 59 months old when the weight-for-height z-score (WHZ) of WHO child growth standards is < –2 standard deviations (SD). It is one of the most prevalent forms of undernutrition and some studies have shown that it also contributes significantly to linear growth restriction or stunting. Studies have shown that a child with severe wasting, also called as severe acute malnutrition (SAM), is up to 12 times more likely to die than a well-nourished child, and the survivors of the episode have increased risk of developing non-communicable chronic disease during adulthood. There is considerable evidence of positive health and nutrition outcomes resulting from integrating nutrition-specific interventions into health systems. The guidance outlines the core principles and standards for providing services for the prevention, early detection, and treatment of child wasting through national health systems. It also outlines essential steps for integrating services for the management of child wasting into routine primary health care services. The purpose of this guideline is to provide practical guidance to support ASEAN Member States in accelerating progress towards the prevention, early detection, and management of child wasting through national health systems, including integrating the treatment of child wasting into routine public health care services. The target audience is policymakers and health and nutrition experts from ASEAN Member States. This guideline is intended to serve as a reference for common regional perspectives on providing services for preventing and treating child wasting through national health systems. Each national health system is unique in its characteristics and structure; therefore, each ASEAN Member State will need to adapt and align these guidelines to reflect its own national context. The guideline is developed according to the latest published 2023 WHO guidelines.