Aim: This review explores the role of purposefully designed and well-integrated therapeutic hospital gardens (THGs) for the benefits of patients, their families, and staff. Background: Significant benefits are realized when people are in contact with nature in the city. Although hospital gardens are prevalent and the beneficial effects of nature on health are widely acknowledged, the establishment of a consistent definition for hospital gardens that promote health is vital to attain reliable and quantifiable health outcomes. Methods: Twenty-eight peer-reviewed journals were critiqued for the period of 2016–2021 and updated with 12 articles from 2021 to 2023 to analyze and synthesize the latest thinking and development in this emergent field. Subsequently, current books and exemplar practice literature were synthesized with the results of the literature review to produce a working definition of THGs. Results: Three themes and 14 subthemes were established showing the interconnectedness of THG definition, user needs and experiences, and the benefits and values of THGs. Two original findings can be established—a need to have a consensus on terminology and to establish design processes. The working definition was produced as a foundational step to guide stakeholders in implementing THGs. Conclusion: THGs can play a role in improving well-being when they are purposefully designed and well-integrated in hospital programs and health policy. Hospital CEOs, designers, and healthcare experts can use the findings and working definition to assist the establishment of such health promoting gardens.