A mild, efficient, and expeditious method has been developed for the synthesis of spiro triazolo[1,2-a]indazole-tetraones via a one-pot three-component reaction of 4-Phenylurazole, isatins and cyclic-1,3-diketones in the presence of a catalytic amount of indium(III) chloride as a Lewis acid catalyst in ethanol at 80 °C conditions. The present protocol offers some advantages such as operational simplicity with easy workup, shorter reaction times, good to excellent yields with superior atom economy and environmentally benign reaction conditions.