AbstractEpidermal growth factor receptor (EGFR) has emerged as an important therapeutic target in many cancers, and overexpression of EGFR is frequently observed in hepatocellular carcinomas (HCCs). Near‐infrared photoimmunotherapy (NIR‐PIT) is a new anticancer treatment that selectively damages the cell membrane of cancer cells after NIR light‐induced photochemical reaction of IR700, which is bound to a targeting antibody on the cell membrane. NIR‐PIT using cetuximab‐IR700 has already been approved in Japan, is under review by the US Food and Drug Administration (FDA) for advanced head and neck cancers, and its safety has been established. However, EGFR has not been investigated as a target in NIR‐PIT in HCCs. Here, we investigate the application of NIR‐PIT using cetuximab‐IR700 to HCCs using xenograft mouse models of EGFR‐expressing HCC cell lines, Hep3B, HuH‐7, and SNU‐449. In vitro NIR‐PIT using EGFR‐targeted cetuximab‐IR700 killed cells in a NIR light dose‐dependent manner. In vivo NIR‐PIT resulted in a delayed growth compared with untreated controls. In addition, in vivo NIR‐PIT in both models showed histological signs of cancer cell damage, such as cytoplasmic vacuolation and nuclear dysmorphism. A significant decrease in Ki‐67 positivity was also observed after NIR‐PIT, indicating decreased cancer cell proliferation. This study suggests that NIR‐PIT using cetuximab‐IR700 has potential for the treatment of EGFR‐expressing HCCs.