"The cardinal is already awake and speaking," said the Rev. John Canary, interim head of the Archdiocese of Chicago.
"I am happy to report good news. The Cardinal is doing well after approximately five hours of surgery," said Dr. Myles Sheehan, chief of the surgical team at Loyola University Medical Center in Maywood, Ill., "We are very hopeful of the best possible result."
Pathologists will determine the extent of the cancer, which was discovered when George found blood in his urine during his vacation in early July.
George, 69, opted to have his entire bladder, prostate gland and lymph nodes removed in a more radical procedure rather than undergo a resection followed by chemotherapy.
Doctors were optimistic all of the cancer had been removed.
"I didn't want chemotherapy because I didn't want to lose my hair," the mostly bald cardinal joked on Wednesday.
George was named archbishop of Chicago in 1997 and elevated by Pope John Paul II to cardinal in 1998.