The complex Ru(bpy)2L2+, where bpy=2,2′‐bipyridine, L=4‐(phenylethynyl)‐2,2′‐bipyridine, was prepared in its racemic and resolved forms (Δ and Λ). The phenylethynyl unit on the bipyridine for the complex acts as a binding site for α‐cyclodextrin in water (1:1 complex, K=3390 L mol−1) or β‐cyclodextrin (2:1 complex, K1=887 L mol−1, K2=8070 L mol−1). The presence of the cyclodextrin provides partial protection to the complex under light‐activated water oxidation conditions. The protectors: A cyclodextrin has been used to protect a specifically designed ruthenium(II) polypyridyl photosensitizer against photodecomposition in water. The enhanced photostability comes from its inclusion at the easiest‐to‐reduce bipyridine ligand, which is consequently the first to be decomposed upon illumination.