Rationale: Gallbladder neuroendocrine carcinoma (GNEC) is indeed a relatively rare malignant tumor of the gallbladder with neuroendocrine differentiation and the ability to produce and secrete a number of neurotransmitters and hormones, characteristics that make its clinical presentation and biological behavior likely to be different from those of other types of gallbladder cancer. Current treatment mostly relies on surgery and adjuvant chemotherapy and radiotherapy. Patient concerns: We report a 53-year-old middle-aged male patient who underwent radical surgery for gallbladder malignancy after a diagnosis of neuroendocrine carcinoma of the gallbladder. Diagnoses: Diagnosis of neuroendocrine carcinoma of the gallbladder based on the return of pathologic findings. Intervention: After local progression of postoperative chemotherapy with the first-line regimen of etoposide + cisplatin, an immune checkpoint inhibitor (traplizumab) + FOLIFIRI (fluorouracil + calcium folinate + irinotecan) regimen was used. Outcomes: The patient achieved 20 months of clinical survival and ultimately died of myelosuppression. Lessons: The use of immune checkpoint inhibitors may become an effective tool in the treatment of neuroendocrine carcinoma of the gallbladder.