This study investigates the green behavior-based teaching practices implemented by Early Childhood Education (ECE) teachers in Binuang District, South Kalimantan, after participating in a 20-day (40-hour) training program organized by the Early Childhood Education Department of the Faculty of Tarbiyah and Teacher Training at the State Islamic University of Antasari. The training covered topics such as the Merdeka Curriculum, active learning models, and lesson designs that support green behavior. The research method used is a case study with semi-structured interviews, classroom observations, and analysis of teaching materials. The results show that the ECE teachers have successfully integrated sustainability values into daily learning activities for children. Through practical learning experiences such as waste sorting, tree planting, and recycling, children develop a sense of responsibility toward their environment. The teachers have applied the 3R principles (Reduce, Reuse, Recycle) and emphasized the important role of parental support in shaping environmentally friendly behavior in children. However, challenges in maintaining consistent sustainability practices were noted, particularly due to the lack of practical guidelines for teachers and high administrative burdens. Additionally, economic barriers faced by parents limit the full implementation of sustainability practices at home. These findings highlight the importance of teacher commitment, community involvement, and parental support in promoting environmental sustainability through early childhood education.