<p>A novel nanocomposite, MWCNTs-MNPs/Met-NiCl₂, was successfully synthesized and characterized for its catalytic activity in alkoxycarbonylation reactions. The construction involved functionalizing multi-walled carbon nanotubes (MWCNTs) with magnetic nanoparticles (MNPs) followed by the incorporation of a metal-NiCl₂ complex. Comprehensive characterization techniques, including FT-IR, XRD, EDX, elemental mapping, TEM, SEM, EDX, ICP-OES, BET, TGA and VSM, confirmed the structural integrity, morphology, and magnetic properties of the catalyst. The catalytic efficiency of MWCNTs-MNPs/Met-NiCl₂ was explored in the synthesis of O-aryl esters through the alkoxycarbonylation of aryl and heteroaryl iodides with Mo(CO)₆ as a carbonyl source, and aryl or heteroaryl alcohols as nucleophiles. The reaction proceeded in an ionic liquid medium, [Bmim][PF₆], under 100&#xa0;°C with KHCO₃ as the base, leading to excellent yields and selectivity. The catalyst exhibited high recyclability and stability, maintaining its efficiency over multiple reaction cycles. This approach presents a sustainable and efficient methodology for the synthesis of O-aryl esters, highlighting the potential of nanocomposite-based catalysts in organic transformations.</p> Graphical Abstract <p></p>