This review offers a comprehensive perspective on income inequality literature in Central–Eastern European (CEE) nations, with a specific focus on six countries: Bulgaria, Romania, Poland, Hungary, Czechia, and Slovakia. By thoroughly examining existing research, this review uncovers the underlying factors and root causes contributing to varying income inequality levels and trends across CEE countries. The investigation is conducted through a systematic literature review and network analysis, focusing on the literature published since 1990, mainly on recent studies. The review is structured around three thematic frameworks (concept and measures, evidence, and causes). These three strands of the literature review not only offer a comprehensive picture of income inequality in CEE countries but also identify critical research gaps for further studies. The review underscores several critical areas for improvement within CEE studies. These include addressing gaps in geographical and temporal coverage, utilizing alternative measurements of income inequality, and investigating the causes of diverging trends in income inequality among CEE countries. Moreover, there is a pressing need to expand the understanding of the determinants influencing income inequality in these nations, which presents a significant opportunity for future research.