The aspects of the climate change mitigation via modernization of the iron and steel industry in Ukraine are discussed. Resources, historic development context, production, and greenhouse gas emissions of the steel sector in Ukraine are analyzed in relation to relevant patterns in the European Union, China, Russia, and worldwide. Several Best Available Technologies, suitable for deployment in Ukraine, are analyzed covering the experience of their implementation in various regions of the world, and their potential for saving energy and cutting carbon dioxide emissions. Two options of modernization with several differently diffused key Best Available Technologies related to sintering, ironmaking, steelmaking, and casting are elaborated, revealing the possibility of cutting the sector’s CO2 emissions in the range of 15.2%–21.8%. Further emissions reduction is possible using a wider range of Best Available Technologies including those related to power generation, rolling mills, etc. The strategic approaches to the sector’s modernization are discussed in the context of global scenarios developed by the International Energy Agency, placing particular emphasis on innovative ironmaking technologies. Modernization of iron and steel industry in Ukraine using Best Available Technologies is analyzed in view of short-term goals and a future need for more radical industrial transformations including commercialization of the novel smelting-reduction ironmaking technologies with higher potential of CO2 emissions reduction.