Carbon emission reduction in the UK’s iron and steel industry, which is responsible for approximately 26% of national industrial emissions, is essential for the UK’s commitment to meet its net zero promise. Hydrogen, as a promising substitute for fossil reductant/fuel, can be utilized in the iron and steel industry to achieve low carbon emissions. In this study, 12 various technical routes that integrate different hydrogen technologies into iron-making processes are modelled and an environ-economic analysis is conducted looking at the carbon emission reduction potential and cost. Considered hydrogen production methods are alkaline electrolysis (AEL), proton exchange membrane (PEM) electrolysis, anion exchange membrane (AEM) electrolysis, bipolar membrane (BPM) electrolysis and seawater (SW) electrolysis and steam methane reforming combined with carbon capture, utilization, and storage (SMR+CCUS), while the considered iron-making processes are hydrogen injection into blast furnace (H₂+BF) and hydrogen-based direct reduction (H-DR). It is found that the only technical route that is unable to reduce carbon emission under any scenario is SMR+H₂+BF. Hydrogen from electrolysis can achieve more effective carbon abatement, but its economic feasibility is significantly influenced by electricity costs and grid carbon intensity. H-DR shows a larger carbon emission reduction potential compared to H₂+BF. Evaluated comprehensively from the aspect of carbon emission reduction effectiveness and cost, SMR+H-DR is the most promising technical route. As the power grid carbon intensity decreased, shifting from SMR+H-DR to Electrolysis+H-DR became a more effective transition route, especially for countries currently relying on high-carbon intensity grids. The impact of the inflation rate on the technical routes is also examined in this study.