To improve the emission and excited-state properties of luminescent cyanometalates, new classes of highly solvatochromic luminescent cyanoruthenium(II) and cyanoruthenate(II) complexes of the general formulae [Ru(PR3)2(CN)2(NN)] and K[Ru(PR3)(CN)3(NN)], respectively, were developed. These complexes could be readily synthesized through the ligand-substitution reaction of K2[Ru(CN)4(PR3)2] with a diimine ligand. The geometrical isomerism of these complexes was characterized by using various spectroscopic techniques. Their photophysical properties, solvatochromism, and electrochemistry have also been investigated. Our detailed study showed that many of these complexes exhibited extremely environmentally sensitive emissions and significantly improved emission quantum efficiencies and lifetimes compared with the well-studied tetracyanoruthenate systems.