By using catalytic amount of CoCl2 with dmgH (dimethylglyoxime) as ligand to form a photosensitizer in situ, a highly selective, efficient, and environmentally benign visible light mediated cross-dehydrogenative coupling (CDC) reaction has been developed in aqueous medium. The desired cross-coupling C-C bonds that involve Csp3 with Csp, Csp2, and Csp3, respectively, were achieved exclusively in high yields without formation of any other byproduct.