Abstract Arylation of amino‐, diamino‐ and triaminophosphines with aryl(mesityl)iodonium triflates under blue light irradiation followed by oxidative P−N bond cleavage in the in situ generated amino phosphonium salts under hydrolytic conditions represent a method for the synthesis of substituted arylphosphine oxides, arylphosphinic and arylphosphonic amides respectively. The proposed approach is based on using visible light as the only promoter for the C−P bond formation, accommodates a variety of functional groups, and can be applied to the late‐stage C−H functionalization of drug molecules.