The obtained L‐Arg‐loaded CaP‐stabilized lipiodol Pickering emulsion (L‐Arg@CaPL) with great emulsion stability can not only neutralize the tumor acidity via reaction of CaP NPs with protons but also enable the release of L‐Arg, thereby synergistically promoting the reinvigoration of exhausted CD8+ T cells and effectively reversing tumor immunosuppression. Here, CD8A is linked to neoplasm.