The embodied carbon (EC) of a building is directly proportional to the materials used and their quantities. Therefore, material selection is a crucial juncture of a building development that cannot be disregarded in attempting to reduce the EC share of whole building lifecycle carbon emissions. Irrespective of that fact, material-related decision-making still relies on the criteria such as cost, time to assemble, quality and durability. It stresses the necessity of taking the carbon content of materials into account as another material selection criterion. If materials are to be chosen optimally, considering several criteria, a multi-criteria decision-making method can be adopted. Of various methods that have been developed, the Analytic Hierarchy Process (AHP) is one tool that has attracted wide attention. In light of that, this chapter adopted the AHP technique to demonstrate how carbon can be included as another decision-making criterion when choosing an optimal material mix for a case study. Depending on the data availability, only material carbon and cost were considered as the selection criteria for the demonstration. Further, the material selection was confined to the building elements that create the structure of the building. The results indicated that the optimum material mix, which was suggested for the building structure, is less expensive and emits considerably lower emissions compared to the material mix that had been originally chosen. Thus, this study informs the building designers and other relevant decision makers that the early consideration of carbon, along with other criteria, would facilitate an optimal selection of material mix for building performance, environmental impact, and occupant well-being. Also, the study provides a good insight into the use of AHP and a practical guide to make trade-off decisions.