A new practical method for the synthesis of tetracyclic pyrido[2′,1′:2,3]imidazo[5,1-a]isoquinolinium compounds by a Yb(OTf)3/AgOTf-catalyzed (Tf = triflate) three-component domino reaction was developed. Significantly, the strategy presents a straightforward and efficient approach to constructing a series of compounds with potent cytotoxic activities.