This review describes the facilitators and barriers impacting on passive access to green spaces within healthcare settings. A systematic mixed-studies review was undertaken to review the quantitative and qualitative evidence on access to green spaces within healthcare settings, as well as to review the methodological quality of the studies eligible for inclusion. A total of 24 articles met the inclusion criteria and were included in the review. The barriers to access were grouped into three themes: “awareness,” “accessibility,” and “comfort.” The facilitators were grouped into 13 themes: “flora and foliage,” “views,” “water features,” “sun, rain, fresh air, wind,” “animal life,” “diverse textures, heights, shapes,” “lawn,” “natural versus artificial material,” “rest areas,” “shade,” “private areas,” “play equipment,” and “safety.” These findings can be explained through multiple lenses, using existing theories on contact with nature and supportive garden design. In an era of elevated stress, patient admissions, and staff turnover in hospitals, and rising costs of providing healthcare services, the creation of settings conducive to health promotion, stress reduction, and faster recovery is relevant and timely. This article, which has collated over three decades of research evidence, is invaluable in addressing this issue.