Kesgin, I. Arbelaez, D. Barzi, E.Z. Gluskin, E. Hasse, Q.B. Ivanyushenkov, Y. Kasa, M. MacDonald, S.W.T. Prestemon, S. Shiroyanagi, Y. Turrioni, D. Zlobin, A.V. JACoW Publishing Geneva, Switzerland The Nb₃Sn-based superconducting undulator (SCU) is a strong candidate to outperform its well-establish counterparts, such as the NbTi-based SCU and cryogenically cooled permanent magnet undulators, over a wide range of undulator period lengths: 10 mm or larger. Thus, the Advanced Photon Source (APS) at Argonne National Laboratory has initiated a project, in collaboration with Fermilab and Berkeley Lab, aiming to establish a robust technology for the fabrication of a Nb₃Sn SCU and validate its operational and radiation performance on the APS storage ring. To accomplish this, first, modeling-driven optimizations were employed to address the magnetic and mechanical design of the undulator magnets, and a series of 4.5-period prototypes subsequently confirmed the design specifications. Then, these short prototypes were successfully scaled to 0.5-m-long magnets, confirming the maximum design field of 1.2 T that is at least 20% higher than a NbTi version with the same gap and period length (9.5 mm and 18 mm, respectively). Fabrication of the final 1.1-m-long magnets is currently underway. Further details will be presented.