CD8A and neoplasm: A novel concept of ultrasound‐driven piezoelectrocatalytic immunoactivation of deep tumor is proposed, and develop a piezoelectric SnS nanosheet to realize highly efficient piezoelectrocatalytic hydrogen generation and lactic acid deprivation, achieving a high outcome of tumor immunoactivation by liberating and activating effector CD8+ T cells as well as high‐efficacy therapy of orthotopic liver cancer.