Systems and methods for building a device graph for cooperative device identification are disclosed. Various information is received at a computing system over a communications network, include information defining a relationship between (i) a unique identifier associated with a first device of a user and (ii) a unique identifier associated with the user, and information defining a relationship between (i) a unique identifier associated with a second device of the user and (ii) the unique identifier associated with the user. The unique identifiers associated with the devices are each mapped to the platform-wide identifier based at least in part on the unique user identifier. A device graph comprising a plurality of device nodes is constructed, with related device nodes connected by one or more edges. Nodes representing the devices are linked based on a relationship identified between them using the platform-wide identifier.