This study investigates the formation of ecological devotion within pesantren, led by kyai in the application of fiqh al-bī’ah. It delineates the developmental stages into three components aligned with Berger and Luckmann’s social construction theory: externalisation, objectification, and internalisation. Using qualitative methods and field studies, data were gathered through semi-structured interviews with three religious leaders from two eco-pesantren in Banten Province. Externalization is exemplified by the kyai’s teachings on humanity as caliphs, advocating against harming the Earth, emphasizing cleanliness as integral to faith, and prioritising thahhārah in fiqh. Objectification is seen in the prohibition of deforestation and embedded environmental preservation duties within the schools’ hidden curriculum. Internalisation reflects practical implementation aligned with established objectives, observed through growing pro-environmental consciousness, attitudes, and behaviours among school members, evolving progressively. This construction of ecological devotion resulted in tangible contributions to groundwater conservation and flood risk mitigation by the two schools. The findings highlight Islamic boarding schools’ potential to elevate environmental standards via fiqh al-bī’ah-rooted ecological wisdom. Collaborative efforts involving stakeholders, such as financial support and training programmes, are vital to enhancing the environmental management capacity, particularly in establishing impactful water management systems within these institutions.