Education for Sustainable Development (ESD) in early childhood education has moved from a peripheral concern to a strategic curricular issue because the early years shape values, dispositions, habits, and foundational understandings that influence later learning and social participation. Recent review studies show that research on sustainability education in early childhood has expanded substantially, with strong emphasis on environmental themes, nature-rich pedagogies, and qualitative inquiry, while intervention studies and holistic integration across social, cultural, and economic pillars remain comparatively limited. This article presents a qualitative systematic review of environment-based learning practices used to integrate ESD into early childhood curricula. Drawing on established review evidence, the study synthesizes major pedagogical trends, curricular logics, implementation patterns, and reported outcomes across the literature. The analysis indicates that effective practices commonly combine time in nature, play-based exploration, guided reflection, social interaction, creative expression, and action-oriented tasks connected to children’s everyday environments. The findings also suggest that most documented outcomes concern environmental literacy, while cognitive, social-emotional, physical, and language outcomes appear as complementary but less consistently foregrounded effects. The review argues that ESD integration in early childhood curricula should move beyond isolated environmental activities toward whole-curriculum, teacher-supported, community-linked, and developmentally appropriate learning designs. These findings offer practical implications for curriculum developers, teacher educators, and researchers, especially in contexts seeking stronger alignment between sustainability agendas and foundational education policy