The Sustainable Development Goals and the World Health Organization have prioritized mental health as an important goal. Mental health is a critical issue within the global public health sphere. Notably, green spaces are a useful alternative for improving mental health. Many studies have focused on green space and mental health, especially on their connection and relationship. However, this research topic lacks a comprehensive and systematic review. Owing to the lack of critical reviews, this study clarified the trend, progress, status, and focus of studies on green spaces and mental health through the use of bibliometric analysis of literature from 2000 to 2022 within the Web of Science database. The literature analysis within this study specifically focused on the following, including the country/region contribution analysis, the institution contribution analysis, keyword analysis, and highly productive journal analysis. Furthermore, this study systematically recorded the content of green space and mental health (i.e., the measurements of green space, psychological instruments for measuring mental health, and the relationship between green space and mental health) and identified the gap that exists and provided future frontier directions or issues for research (i.e., the quantification of elements from health-oriented green space planning, the equity of green space, and the long-term effects of green space on mental health). These contribute toward comprehending the progress and content of this research topic and further provide a guide, reference, and inspiration for possible future research.