In the process of drug discovery and development, an efficient and expedient synthetic method for imidazole-based small molecules from commercially available and cheap starting materials has great significance. Herein, we developed a TMSOTf-catalyzed synthesis of trisubstituted imidazoles through the reaction of 1,2-diketones and aldehydes using hexamethyldisilazane as a nitrogen source under microwave heating and solvent-free conditions. The chemical structures of representative trisubstituted imidazoles were confirmed using X-ray single-crystal diffraction analysis. This synthetic method has several advantages including the involvement of mild Lewis acid, being metal- and additive-free, wide substrate scope with good to excellent yields and short reaction time. Furthermore, we demonstrate the application of the methodology in the synthesis of biologically active imidazole-based drugs.