In the interest of mitigating global warming and climate change, the leading industrial sectors such as the iron and steel industry, as one of the most significant industrial contributors to anthropogenic CO2 emissions, is challenged to find more efficient and environmentally clean solutions to reduce their CO2 emissions while maintaining high process efficiencies and low production costs. To find new ways of reducing CO2 or other emissions to air, water and soil, Life Cycle Assessment (LCA) methodology can be employed to trace and quantify the most significant sources of emissions, starting from the raw-materials extraction to the final product's usage/disposal. In this work, a “cradle-to-gate” LCA study was performed, according to CML 2001 impact assessment method, for an integrated steel mill with and without carbon capture and storage (CCS). Two post-combustion CO2 capture technologies: a conventional chemical absorption technology using mono-ethanol amine (MEA) and a more innovative one based on calcium looping (CaL) are evaluated and compared against the benchmark case represented by the integrated steel mill without CCS. All results are reported on the basis of one metric ton of hot rolled coil (HRC) produced. Analysing the most significant environmental impact categories leads to the conclusion that integrating CCS into the steel production route, decreases the global warming potential in the range of 47.98–75.74%. Generally, the decrease of CO2 emissions goes along with an increase of the other impact categories regardless of the technology used, as the adoption of CCS technologies leads to efficiency losses, which, in turn, brings additional fuel demand and related other emissions. Among the investigated capture technologies, CaL shows significantly better environmental performance than the conventional amine-based CO2 capture technology as the decrease observed in eight of the environmental indicators, other than GWP, is between 2.90% and 48.87% compared to the case when MEA is applied.