Site-specific functionalization of sp³ CH bonds adjacent to a nitrogen atom is one of the unexplored heterogeneous transformations. Aiming at α-arylation of glycine derivative for rapid access to indolylglycines without the aid of bases, a chemically robust and two-dimensional COF is prepared. Integration of [2,2′]bipyridyl (Bpy) unit benefits active homogeneous complex Ru(Bpy)₂²⁺ to anchor over the framework backbone to devise Ru-COF that acts as unprecedented visible light photocatalyst towards cross-dehydrogenative coupling of secondary amines with indoles in excellent yield at room temperature, under aerobic condition. Ru-COF shows admirable reusability and superior activity to that of Ru(Bpy)₃Cl₂, while substrate variation studies delineate wide ranges of functional group tolerance. To the best of Ru-COF, atom-economic CH functionalization is realized as iminium ion is in situ generated. The photocatalytic route is detailed from astute modulation of optical band-gap in light of density-functional theory studies and experimental results, which validates single-electron-transfer pathway.