The present study seeks to provide an overview of studies dealing with the grey systems theory from the perspective of socio-economic systems. A scoping review is conducted to explore the studies focusing grey systems theory and its applications in socio-economic systems. The publications selected for analysis were collected through searching the databases of the Web of Science, Scopus, and Science Direct. The publications were selected from 2010 to 2019, and the following keywords were used to detect them: grey systems, grey relational, grey model, grey prediction, grey control, grey incidence, grey cluster, grey decision, and grey input-output plus social, economic, and socioeconomic. Out of the 2375 records found, 147 full papers were screened. Results obtained from the studies were separated into the following categories: social network, healthcare, financial issues, sustainability, tourism, social and cultural, public sectors, urbanization, development, business, economics, demographics, innovation, and entrepreneurship. Findings showed that complexity, uncertainty, and a lack of access to a large collection of data directed researchers to rely on grey systems theory-based socio-economic systems. Furthermore, theory-based grey systems were more effective than other approaches of decision-making and analysis. Drawing on the grey systems theory-based holistic approaches and systems thinking methods helped to obtain better results in analyzing socio-economic systems.