<p>This methodology introduces the construction of a reusable Cu(I)-based magnetic nanocatalyst, Fe₃O₄@SiO₂-Dop/DPM-CuI, via co-precipitation followed by sequential surface functionalization. This catalyst features a robust core–shell architecture, as confirmed by structural and chemical characterization techniques, including FT-IR, XRD, XPS, and EDX. The catalyst demonstrates high thermal stability and mesoporous properties, advantageous for catalytic applications. Its strong magnetic responsiveness allows for easy magnetic separation and excellent reusability, maintaining structural integrity after eight cycles. The catalyst excels in the C–H arylation of benzoazoles with iodobenzene derivatives, achieving high yields (84–99%) under mild, environmentally friendly conditions using PEG/H₂O as the solvent. This heterogeneous system showcases a broad substrate scope, TON and TOF, and minimal metal leaching. Benzoazoles, which include significant compounds in pharmaceuticals and industry, benefit from this efficient synthetic method that overcomes the limitations of traditional C–H arylation methods, which often require expensive catalysts and harsh conditions. The development of this Cu(I)-based magnetic catalyst highlights its potential for sustainable organic synthesis, providing an eco-friendly alternative for the functionalization of benzoazoles.</p> Graphical Abstract <p></p>