The research aims to identify industrial and other economic sectors’ contribution to the regional divergence in Eastern European countries, particularly Poland and Ukraine. The ambiguity of the results of previous studies on the factors of regional convergence indicates the need for further research, considering the peculiarities of distinct economies’ development. The countries selected for analysis – Ukraine and Poland – had similar starting conditions for market transformation, have a common border, and a comparable population. The analysis of regional inequality in Ukraine revealed a tendency of asymmetric regions’ growth in 2010–2017. In Poland, divergent trends in regional development in 2009–2017 were significantly less pronounced. The statistical method to identify the impact of the industrial, agricultural, and service sectors on regional σ-convergence based on coefficients of variation measuring the differences in regional economies’ sectoral structure was used. The analysis demonstrated that, in general, the uneven structure of regional economies does not significantly impact any of the analyzed countries, which confirmed the results of some other studies. Simultaneously, it highlighted that the industrial sector had the greatest impact on regional divergence in Poland. Despite the dominant role of services in regional divergence in Ukraine, most researchers emphasize the importance of the industrial sector for regional development. To consider this factor in the regional divergence of Ukrainian regions, some regional policy implications were considered.