A Copper(II) complex was synthesized using Indolic Schiff base and 1,10-phenanthroline, immobilized on MCM-41 to yield a selective, efficient, and reusable heterogeneous catalyst. Physicochemical properties were characterized via FT-IR, UV–Vis DRS, PXRD, SEM, EDX, ICP-OES, TEM, N2 adsorption-desorption, TGA, 13C MAS-NMR, and XPS. The catalyst's efficiency was tested in imidazoindole reactions with various aldehydes, isatin, and ammonium acetate in ethanol at room temperature for 30 min, showing reusability up to six runs. The catalyst achieved good to excellent yields for diverse substrates, including electron-donating, electron-withdrawing, disubstituted, fused, conjugated, heterocyclic, and aliphatic aldehydes.