John McCain was born on August 9, 1884, in Teoc, Mississippi. He graduated from the U.S. Naval Academy in June 1906 and was commissioned an Ensign in 1907. His first years were served on the Great White Fleet's world cruise from 1907 to 1909, followed by service aboard ships in the Asiatic Squadron. He served on the armored cruiser USS San Diego (ACR-6) during the occupation of Vera Cruz in the Mexican revolution and throughout World War I while on Atlantic escort duty. After the war, McCain served aboard the battleships USS Maryland (BB-46) and New Mexico (BB-40), and then on the ammunition ship USS Nitro (AE-2), before taking command of the cargo ship USS Sirius (AK-15). He was designated a Naval Aviator in 1936 and commanded the aircraft carrier USS Ranger (CV-4) from 1937 to 1939. He served as commander of the Aircraft Scouting Force of the Atlantic Fleet from January 1941 to May 1942, and then was appointed commander of Aircraft South Pacific, where he served until October 1942. He was then assigned as Chief of the Bureau of Aeronautics, serving from October 1942 to August 1943, when he was made Deputy Chief of Naval Operations for Air. ADM McCain returned to the Pacific Theater in August 1944 and commanded a fast carrier task force for the final year of the war, where he participated in most of the final battles that helped end World War II. He died shortly after the war ended, on September 6, 1945. John McCain was married to the former Catherine Davey Vaulx of Fayetteville, Arkansas, and his son, John S. McCain, Jr., was also an Admiral in the U.S. Navy, making them the only father and son to achieve that rank. His grandson is Senator John S. McCain, III.

His Navy Cross Citation reads:

The President of the United States takes pleasure in presenting the Navy Cross to John Sidney McCain, Vice Admiral, U.S. Navy, for extraordinary heroism and distinguished service in the line of his profession as Commander, Task Group 38.1, after the torpedoing of the U.S.S. CANBERRA and U.S.S. HOUSTON by Japanese aerial forces, ninety miles off the Island of Formosa, during the period 13 to 15 October 1944. Vice Admiral McCain interposed his task group to cover the withdrawal of the U.S.S. CANBERRA and U.S.S. HOUSTON and by his skillful and courageous handling of his forces broke up repeated heavy enemy air attacks. His actions contributed in great measure to the ultimate successful salvaging of the two damaged cruisers. Vice Admiral McCain's inspiring leadership and the valiant devotion to duty of his command contributed in large measure to the outstanding success of these vital missions and reflect great credit upon the United States Naval Service.