Fibre-reinforced concrete has been used in structures without any additional reinforcement when the design is determined by transient load stages (precast segments for tunnels), in elements with favourable boundary conditions, and in structures subjected to low load levels (pavements or pipes). Recently, the material has been used as the primary reinforcement in elements with greater structural responsibility, such as building column-supported slabs. Several dozen buildings have incorporated this new technology, and research is being conducted on how to optimise the design whilst guaranteeing the required reliability levels. However, in some cases, fibres have not been used as the primary reinforcement in concrete slabs for economic reasons. In most cases, the solution is compared with existing alternatives (traditionally reinforced concrete) considering only the direct material costs and disregarding indirect costs, social aspects and environmental factors. The building construction sector lacks sustainability rating tools to assess structural components separately (e.g. columns, floors, panels, façades). This paper presents a new method that can be used to assess the sustainability of concrete slabs by means of a multi-criteria decision-making approach including fibre-reinforced concrete. To this end, it uses rigorous analyses of current concrete slab technologies and sustainability assessment tools. Criteria, indicators, weights and value functions have been specifically selected, defined and calibrated for this research.