OBJECTIVE The objective of this review was to identify and characterize the use of the natural environment/outdoor space by occupational therapists working in mental health care. This included consideration of the characteristics of the environment used, interventions, mental health conditions being treated, and the outcomes being considered. BACKGROUND Research has demonstrated that there is a link between human health and the environment. The benefits appear to be particularly relevant to people with mental health conditions. Occupational therapists already consider the environment when assessing and developing interventions, and therefore are well placed to consider and use the natural environment in mental health practice. However, the use of the natural environment by occupational therapists working in mental health is unclear. METHODS The scoping review included any publication relating to the use of the natural environment/outdoor space in mental health occupational therapy practice. All forms of the natural environment or outdoor space were included, such as hospital gardens and local parks. There were no geographical, gender, or age restrictions. All mental health diagnoses were eligible for inclusion. METHODS Seven databases were searched: Embase (Ovid), Emcare (Ovid), MEDLINE (Ovid), PsycINFO (ProQuest), AMED (Ovid), Trip Database, and CINAHL (EBSCOhost). Gray literature was also searched using a selection of websites and digital repositories. Papers written in English were searched, with no time limit set on publication. Titles and abstracts were screened by 2 independent reviewers for assessment against the inclusion criteria, followed by a full-text review and data extraction. Data were extracted using the data extraction tool developed by the authors. Findings were presented in a tabular format, accompanied by a narrative summary describing how the results relate to the review objectives and question. RESULTS Of peer-reviewed publications, 7 papers used qualitative methods and 7 used mixed methodology. The remaining sources included conference abstracts, unpublished works, a book chapter, and a website article. The environments used included forests, beaches, gardens, and parks. A variety of interventions were delivered in these environments, including gardening and nature-based activities, physical activities, and animal-assisted interventions. Such activity-focused interventions are largely delivered in a group context, thus providing a social element. A diverse range of mental health conditions were treated. Several methods were used to consider the outcomes on the individual, including both qualitative measures and quantitative outcome measurement tools. CONCLUSIONS The review highlights many characteristics of how the natural environment is being used across mental health services by occupational therapists. A variety of conditions are targeted for such interventions, and several outcome measures have been used to understand impact. This review can support further development and implementation of nature-based approaches in mental health occupational therapy.