The use of unmanned aerial system (UAS) in congested airspace and/or in the proximity of critical infrastructure poses several challenges as far as safe and secure operations are concerned. The paper provides a detailed description of the architecture and workflow of a platform for UAS traffic management (UTM), designed to pave the way for increased, improved and safer UAS operations in the civil airspace. In particular, access to low-altitude airspace for UAS operations is managed, while facilitating the implementation of beyond visual line-of-sight (BVLOS) operations, and ensuring a safe and efficient integration of UAS into both controlled and uncontrolled airspace. Detection and management of unidentified or uncooperative UAS’s is also taken care of. To this end, an architecture based on three interacting layers is proposed, with the air traffic control at the highest level, the UAS operator(s) at the bottom, and a UAS service supplier acting as an interface. The platform, with its physical and digital elements, guarantees the effective and efficient interaction among these three layers, including management of contingency scenarios, which require a variation of admissible flight volumes for UAS operations and/or fast trajectory re-planning. The platform, developed within a research project which involved several partners, was tested in a relevant operational scenario at the Grottaglie–Taranto airport in Italy. The operators involved in the tests provided positive feedback on the services provided by the platform and the usability of the interfaces, while also making suggestions for adding new features in future developments.