An efficient green synthesis of tetrahydrobenzo[4,5]imidazo[2,1-b]quinazolin-1(2H)-ones has been achieved under solvent-free conditions by the reaction of 1H-benzo[d]imidazol-2-amine, various aldehydes and 1,3-dicarbonyl compounds in the presence of molybdate sulfuric acid (MSA) as a catalyst. Higher product yields were isolated easily using this reusable MSA catalyst, and environmentally benign reaction conditions in shorter reaction time are the merits of this reaction. All the newly synthesized compounds were tested for their anti-oxidant and anticancer activities. Most of them showed good to excellent bio-activity in both the experiments.