<p>An easy and effective one-pot method was utilized to synthesize benzimidazole derivatives using a heterogeneous Brønsted acidic ionic liquid catalyst ([MCM-41-(PSim)][SO₄H]) supported on MCM-41, which was derived from rice husks. Initially, MCM-41 was modified using 3-(chloropropyl)triethoxysilane. The modified material, MCM-41-(CPS), was then reacted with imidazole to yield the compound [MCM-41-(PSim)][Cl]. This was followed by acidification with 0.5 M sulfuric acid to generate Brønsted acidic ionic liquid ([MCM-41-(PSim)][SO₄H]). Characterization of the new catalyst was conducted using FTIR, XRD, N2 adsorption–desorption analysis, TGA/DTG, and SEM–EDX. Utilizing the prepared catalyst, a diverse range of aldehydes and carboxylic acids were synthesized to produce benzimidazole derivatives. The catalyst can be easily recovered and synthesized with high yield under mild conditions and short reaction times, making this method economically viable for the preparation of benzimidazole derivatives.</p>