Visible-light-induced C-H phosphorylation of para-CAr-H and heteroarenes was realized using cost-effective RuCl3 as a catalyst. The reaction conditions are green and environmentally friendly, using water as a solvent at room temperature and without ligands. A broad range of highly functional organophosphorus compounds were obtained via a cross-dehydrogenation-coupling (CDC) reaction. In addition, we also proved that RuCl3 is a photocatalyst via its absorption spectrum and on/off light experiments.