This article considers entropy analysis as a tool for assessing the sustainability and integration of regional economies into national and international economic systems. Three key types of entropy are defined – economic diversification, income and employment distribution and interregional ties. The methodology for calculating entropy indicators based on the generalised Shannon entropy formula is presented. A comparative analysis of three hypothetical regions was conducted on the basis of entropy indices. The obtained results allow us to quantitatively assess the specifics of regional development, identify imbalances and propose strategies to improve the sustainability and economic diversification of regions.