Gastric cancer remains a considerable global health burden, with limited treatment options available for advanced cases, especially for superaged patients. Cadonilimab, a first-in-class bi-specific antibody (BsAb), offer a promising immunotherapy approach by targeting PD-1/CTLA-4 simultaneously. Herein, we present a case report of an 85-year-old patient with HER2-negative advanced gastric cancer who received first-line treatment with cadonilimab combined with chemotherapy, but cadonilimab was discontinued due to the observation of immune-related pneumonitis during treatment. Despite these changes, the patient still exhibited a stable disease condition for a year until now. This case report highlights the potential of cadonilimab in the treatment of superaged patients with advanced gastric cancer, while the efficacy and safety of it need to be further evaluated.