In aspects of object tracking based on UWB tags, a system includes ultra-wideband (UWB) tags located for association with respective objects in an environment, where each UWB tag is identified with a digital label indicative of the association with one or more of the objects. A tracking service is implemented to receive initial location data for the objects from each of the UWB tags that are associated with the objects, and generate an object identity database in which each of the objects are identified by their respective initial location data. The tracking service can monitor for movement of an object that is identified by the initial location data based on subsequent positioning data associated with the object. The movement of an object is monitored for an unauthorized relocation of the object, for a cluster of multiple objects moving together, and/or for an abnormal proximity of multiple objects in the environment.