Despite progress toward sustainability, it remains uncertain how we as a global society will make transformations needed at scale. We argue that intentionally involving children in sustainability efforts may catalyze promising changes in how we approach human-environmental crises. This involvement, however, entails much more than the traditional focus on exposing children to environmental education or sustainability learning. Here, we present a pathway where children move through incremental yet fluid stages, from rich experiences in nature in early childhood, to reflective activities, leadership development, and formal opportunities in sustainability governance in later childhood and adolescence. Each stage requires overcoming distinct barriers that vary across and within countries: we identify and discuss these main barriers, and suggest potential ways the sustainability sciences community can help to reduce them. We offer this proposed pathway as a first step toward ensuring young people's involvement, agency, and stewardship in achieving global sustainability.