Although the Coronavirus Disease 2019 (COVID-19) pandemic has tended to be influenza-liked, the infection remains a significant hazard to cancer patients. This paper presents three cancer patients diagnosed with COVID-19 in 2021 who received the herbal medicine Jing Guan Fang (JGF) alongside Western medicine during isolation or hospitalization. The treatment effects of the herbal medicine were evaluated. The patients aged between 40 and 60 years. Two of them were stage II breast cancer patients, and one was a stage IV lung cancer patient. Their COVID-19 severity ranged from mild to moderate, and the initial symptoms included fever, anosmia, dyspnea, and cough. Following the administration of JGF, their symptoms did not deteriorate, and they recovered. These cases showed that early administration of JGF can shorten the hospitalization and clinical course of the infection in cancer patients. We conclude that herbal medicine can help relieve symptoms of COVID-19 infection in cancer patients.