A series of tetracyanoruthenate(II) with chelating pyridyl N-heterocyclic carbene ligands (NHC-py) was synthesized and characterized. Their photophysical and electrochemical properties as well as the photochromic behavior of their dithienylethene-containing complexes were studied. Photocyclization was found to take place upon irradiation into the metal-to-ligand charge transfer (MLCT) absorption bands of these complexes, and evidence is provided to support the triplet-sensitizing reaction pathway.