The purpose of this paper is a multidimensional assessment of the diversification of economic development in EU countries in the context of the progress in the implementation of the concept of sustainable development in 2014 and 2019. The issues discussed in this article are topical and important, given that the spatial disparity of economic development in the EU has never been so pronounced as it is today. While there is a wealth of studies on economic development in the literature, research on the comprehensive approach to this problem in the relation of sustainable development appears to be rather scarce. The article emphasizes the role of energy in economic growth. Authors used taxonomic measures. They were constructed on the basis of selected methods of multidimensional comparative analysis. By using the Hellwig method and the TOPSIS method, taxonomic measures were constructed, and linear ordering of the EU countries was carried out. In addition, using the so-called threshold method, the clustering of EU countries was carried out. The analysis involved 27 EU countries. The conducted research revealed significant disproportions between the respective EU countries in terms of the level of economic development in the relation of implementing the concept of sustainable development. It seems justified to take action aimed at eliminating the differences between the countries in the analyzed aspect. It is necessary both to intensify efforts at the level of individual Member States and the EU, oriented towards pro-development activities.