The total number of cancer patients who are eligible for and will benefit from immune checkpoint inhibitors (ICIs) in China has not been quantified. This cross-sectional study was conducted to estimate the number of Chinese cancer patients with eligibility and response to ICIs based on the 2015 Chinese cancer statistics and the immune checkpoint inhibitor clinical practice guideline of the Chinese Society of Clinical Oncology. A total of 11 ICIs were recommended for 17 cancer types. The estimated number of eligible patients annually was 1 290 156 (55.18%), which included 888 738 males (60.05%) and 400 468 females (46.67%). The estimated number of responders annually was 448 972 (19.20%), which included 309 023 males (20.88%) and 139 764 females (16.29%). Gastric cancer (n=291 000, 12.45%), non-small-cell lung cancer (n=289 629, 12.39%), and hepatocellular carcinoma (n=277 100, 11.85%) were the top three cancer types with the highest number of eligible patients. Non-small-cell lung cancer (n=180 022, 7.70%), hepatocellular carcinoma (n=75 648, 3.24%), and small-cell lung cancer (n=64 362, 2.75%) were the top three cancer types with the highest number of responders. In conclusion, ICIs provide considerable benefit in Chinese cancer patients under optimal estimation.