The building industry is one of the most resource-intensive sectors in industrialized countries, requiring a shift from a linear to a more sustainable circular economic model. Nevertheless, there are several major challenges, such as the management of information regarding used materials and products, the lack of cross-sector documentation tools, and sales operations for implementing a dynamic circular economy in the building industry. To overcome these challenges, blockchain technology for documentation, tracing used materials and products, and the use of multi-criteria decision-making approaches for the ranking and selection of optimal used materials and products have emerged as crucial facilitators, with the potential to address the technological, organizational, environmental, and economic requirements. The purpose of this study is to develop a theoretical framework of a digital platform ecosystem for implementing a dynamic circular economy in the building industry through the integration of blockchain technology and a multi-criteria decision-making approach built upon their synergy. The priority order of two alternatives of used materials and products was determined according to the AHP method, leading to selection of the most sustainable alternative. This research study contributes to dynamic circular economies by (1) facilitating cross-sector information transparency and the tracing of used materials and products from their sources to their end-of-life stages and through (2) the ranking and selection of used materials and products based on their overall properties.