Eating disorders are among the mental health conditions contributing to the highest mortality rates globally. Indonesia ranks 4th in the world in terms of the number of eating disorder patients. Despite the high prevalence of eating disorders in Indonesia, many people still associate their causes solely with milieu and social factors. However, this assumption is incorrect, as several types of eating disorders have been proven to have links to the biological genes present in the human body. Individuals with eating disorders require serious and comprehensive care. The design of rehabilitation centers for eating disorder patients must be capable of responding to their cognitive conditions, including emotional states and behavioral patterns. Unfortunately, current rehabilitation facility designs often fail to fully address these individual needs. This highlights the urgency for a specific design framework that aims to produce environments that are both ideal and sustainable. Gunderson’s 1978 milieu therapy principles, originally developed as behavioral treatment strategies for psychiatric wards, offer a promising foundation for addressing users’ emotional and behavioral needs through healthcare instruments services. By conducting a deeper analysis of these principles and translating them into spatial elements, it is possible to formulate a design guideline that effectively responds to both the emotional and behavioral dimensions of individual users. Ultimately, this approach seeks to create a sustainable healing environment, one that not only supports therapeutic goals but also fosters long-term emotional stability and psychological recovery of the wellbeing.