We describe a simple protocol for the synthesis of (E)‐β‐aminoacrylonitriles via Cu(OAc)2‐mediated nucleophilic addition of secondary amines to 1,2,3‐triazine 1 and an aerobic oxidation reaction. The reactions, which were studied with a broad substrate scope, are effective with cyclic, heterocyclic, aliphatic, allylic, and benzylic amines as well as l‐proline derivatives. The reactions use catalytic Cu(OAc)2 to promote 1,2,3‐triazine addition with various secondary amines, followed by in situ loss of nitrogen and subsequent imine oxidation to generate the corresponding (E)‐β‐aminoacrylonitriles in good yields with excellent stereoselectivities. These copper(II)‐mediated aerobic oxidation reactions proceed under mild reaction conditions by oxidation of the Cu(II) species using molecular oxygen to complete the cycle without the participation of ligand, base or chemical oxidant additives.