In the title compound, [Cu(ClO4)(C2H3N)(C15H19N3O)]ClO4, the CuII ion is coordinated by three N atoms and a hydroxyl-O atom of the tetradentate ligand, an O atom of a perchlorate ion and an N atom of an acetonitrile ligand giving a tetragonally distorted octahedral environment around the copper(II) atom. There is an offset inter-complex face-to-face π–π interaction [centroid–centroid distance = 3.718 (2) Å] involving one of the pyridine rings of the ligand as well as an intra-complex O—H⋯O hydrogen-bonding interaction between the coordinated hydroxyl group of the ligand and the perchlorate counter-ion