The　poor　resistance　of　high-density　polyethylene　(HDPE)　to　thermal-oxidative　aging　and　ultraviolet　(UV)　degradation　significantly　limits　its　service　life.　In　this　study,　the　nanocomposite　ZnO-AO　was　synthesized　using　γ-glycidoxypropyltrimethoxysilane　(GPTMS)　as　a　bridging　agent,　which　facilitated　the　loading　of　a　significant　quantity　of　the　hindered　phenolic　antioxidant　(AO)　onto　the　surface　of　ZnO　nanoparticles,　and　the　HDPE/ZnO-AO　composites　were　subsequently　prepared　by　melt　blending.　The　results　indicated　that　the　combination　of　ZnO　and　AO　was　synergistic,　and　the　more　optimized　para-substituent　structure　of　AO　significantly　reduced　the　hydroxyl　bond　dissociation　energy　(BDE)　of　the　hindered　phenols,　thereby　enhancing　antioxidant　activity.　Additionally,　the　hydroxyl　groups　on　the　surface　of　ZnO　were　substituted　with　AO,　which　improved　the　particle　dispersion.　After　400　h　of　UV　aging,　HDPE/ZnO-AO　retained　78.36　%　and　95.92　%　of　its　elongation　at　break　and　impact　strength,　respectively,　compared　to　only　2.25　%　and　6.17　%　for　pure　HDPE.　After　28　days　of　thermal-oxidative　aging,　the　carbonyl　index　of　HDPE/ZnO-AO　increased　by　only　0.18,　significantly　lower　than　that　of　HDPE　(0.43).　Accordingly,　the　ZnO　and　AO,　covalently　linked　by　GPTMS,　demonstrated　enhanced　performance　compared　to　individual　original　capabilities,　successfully　integrating　efficient　thermal-oxidative　stability　and　UV　protection.　This　study　provides　a　promising　approach　for　the　development　of　long-lasting　HDPE　composites.　©　2025　Elsevier　Ltd