Utilizing [Ru(bpy)₃]Cl₂ as a photoredox catalyst and a blue LED as an irradiation source, moderate to good yields of 6-arylphenanthridines were obtained from aryl diazonium salts in situ formed from the reactions of N-(2-aminoaryl)benzoimines and tert-butyl nitrite (tBuONO). Although few visible light-mediated protocols are available for the synthesis of 6-arylphenanthridines, this work provides a new method to access them readily from inexpensive and environmentally benign starting materials.