To accelerate Circular Economy (CE) implementation in the built environment, integrated information systems that are capable to identify, coordinate, and evaluate CE collaborations across heterogeneous projects are in demand. A digital collaborative hub, Circularity Information Platform (CIP), is a promising solution to streamline complex information exchanges and foster symbiotic material interactions in broader circular ecosystems. However, there is a lack of comprehensive design blueprints of CIP supported by empirical development evidence. We aim to design, prototype, demonstrate, and evaluate a Reference Architecture (RA) of CIP using a design science research methodology. The proposed RA is used to instantiate a web-based artifact of CIP for a concrete supply chain in The Netherlands. The artifact is evaluated by industrial and governmental actors through workshops. The evaluation results confirm that (1) the proposed RA models contribute to effective CIP development, and (2) the identified functionalities of CIP are beneficial to CE implementation.