Campus Blue-Green-Grey Spaces and College Students’ Health: A Systematic Review

University students often face various stressors that impact their physical, mental, and social well-being, raising concerns about the long-term sustainability of student health in higher education settings. Growing evidence suggests that exposure to campus green and blue spaces has significant health benefits. However, empirical studies evaluating the health effects of campus outdoor grey spaces (playgrounds, roads, squares) remain limited. Grey spaces are identified as grey in a material sense (urban, concrete, artificial, constructed). This systematic review synthesizes empirical research on the associations between outdoor campus spaces and student health, with implications for sustainable campus planning. Following the PRISMA protocol, 60 studies were identified and included from four databases (Scopus, Web of Science, ScienceDirect, and PubMed). The results were as follows: (1) Research in this field has increased over the past five years, with Asia (particularly China) contributing the largest share of studies; (2) The research topics were diverse, covering five major themes of campus outdoor spaces and 28 student health indicators; (3) The measurement of environmental and physical–mental health combined subjective assessments with objective data, whereas social health primarily relied on self-reported subjective perceptions; (4) Campus outdoor spaces affected university students’ health by promoting physical activity, modulating physiological responses, alleviating stress and cognition, and providing opportunities for social interaction and solitude. Campus outdoor spaces contribute to students’ sustainable well-being in various ways. Green and blue spaces provide significant psychological restorative benefits, while grey spaces play a crucial role in promoting physical activities and social interactions, thus warranting greater attention in campus planning. These findings highlight the importance of designing equitable, multifunctional blue-green-grey spaces to support healthier and more sustainable university campuses.