<p>Pickering emulsions with antioxidative properties have significant applications across various fields such as biomedicine, skincare, and food. The fabrication of antioxidant Pickering emulsions using core cross-linked diblock copolymer nanoparticles bearing polyphenol groups as both Pickering emulsifiers and the interfacial reservoirs of antioxidants was demonstrated in this study. Poly[oligo(ethylene glycol) methyl ether methacrylate]₁₈-poly(diacetone acrylamide)₅₀ (POEGMA₁₈-PDAAM₅₀,&#xa0;E₁₈D₅₀) diblock copolymer nanoparticles were first synthesized via RAFT-mediated dispersion polymerization in water. Subsequently, PDAAM cores of E₁₈D₅₀ were chemically cross-linked using 4,6-diaminoresorcinol dihydrochloride (DAR.2HCl) as the cross-linker. The cross-linking process involved the Schiff base reaction between carbonyl groups of the PDAAM core-forming blocks and the amine groups of DAR.2HCl. Polyphenols were readily introduced into the cores of nanoparticles while the cross-linking of PDAAM core, affording core cross-linked copolymer nanoparticles bearing polyphenols (CCE₁₈D₅₀-P). The prepared CCE₁₈D₅₀-P nanoparticles exhibited excellent emulsification performances and outstanding free radical scavenging ability. Antioxidant dodecane-in-water Pickering emulsions were formulated using CCE₁₈D₅₀-P as Pickering emulsifiers, which demonstrated a desired effect in preserving vitamin E, with retentions of 88.4% and 82.1% after 28&#xa0;days and 45&#xa0;days of storage at room temperature, respectively.</p> Graphical Abstract <p></p>