<p>Suzuki-Miyaura cross-coupling under aqueous biphasic conditions remains challenging due to limited interfacial mass transfer and catalyst deactivation. Although Pickering emulsions offer a practical solution by creating large and stable oil–water interfaces, integrating emulsion stabilization and catalytic activity into a single solid material remains nontrivial. Herein, we develop palladium nanoparticles supported on poly(1-vinylimidazole)-grafted graphene oxide (Pd/mGO-PVIm) as a catalyst that combines interfacial stabilization with catalytic activity for aqueous Suzuki-Miyaura coupling. Poly(vinylimidazole) was grafted onto graphene oxide to regulate amphiphilicity and introduce nitrogen coordination sites, enabling stable oil-in-water Pickering emulsions while enhancing Pd dispersion via Pd−N interactions. Consequently, Pd/mGO-PVIm shows improved catalytic efficiency compared with conventional biphasic systems. Under optimized conditions, it delivers near-quantitative conversion of aryl iodides in pure water at 0.0017 mmol Pd, with a turnover frequency (TOF) of 507,740&#xa0;h⁻¹ calculated from the initial rate. The catalyst exhibits broad substrate scope and retains activity over multiple cycles. This work provides a green and efficient approach for biphasic Suzuki coupling.</p> Graphical Abstract <p></p>