Cardinal George "went right back to work" after his treatment, according to the Chicago Archdiocese.
Cancer was found in his right kidney and liver last month. He had surgery to have the cancerous nodule removed from his liver, but will undergo four months of chemo in three-week cycles.
Bladder cancer is the fifth most common form of the disease, especially among older men.
Cardinal George had his bladder removed due to cancer in 2006.