Blue–green space (BGS) is an important component of the Earth's environment, and BGS research and practice have become an increasingly important part of climate change adaptation and mitigation. In this review article, we conducted a bibliometric assessment on the science and practice of BGS worldwide. Our results showed that (1) the number of BGS studies has been growing rapidly since 2017, and the intensity of international collaboration has increased markedly; (2) BGS research hot spots were ignited by and focused on environment problems and evolved over time. Examples include, but are not limited to, boosting the composite functions and synergistic effects of BGS in climate change adaptation and mitigation (particularly stormwater management and thermal environment regulation), enhancing ecosystem services (biodiversity and carbon), and promoting human health (physical and mental); (3) the collaborative planning and system construction of BGS will be a major development trend in the future; and (4) research on synergistic mechanisms, collaborative planning, and BGS spatial pattern optimization has largely been theoretical, and there is a shortage of empirical quantitative research and there are few real-world examples of BGS in socio-ecological practice. These set the stage for further advancement of BGS science and practice.