Kearsarge became flagship of the North Atlantic Station, cruising down the Atlantic seaboard and in the Caribbean Sea. From 3 June 1903 to 26 July 1903 she served briefly as flagship of the European Squadron while on a cruise that took her first to Kiel, Germany. She was visited by Emperor Wilhelm II of Germany on 26 June 1903 and by the Prince of Wales -- who would later become King George V of the United Kingdom -- on 13 July. She returned to Bar Harbor, Maine, on 26 July 1903 and resumed duties as flagship of the North Atlantic Fleet. She sailed from New York 1 December 1903 for Guantanamo Bay, Cuba, where, on 10 December, the United States took formal possession of the Guantanamo Naval Reservation. Following maneuvers in the Caribbean Sea, she led the North Atlantic Battleship Squadron to Lisbon, Portugal, where she entertained the King Charles of Portugal on 11 June 1904. She next steamed to Phaleron Bay, Greece, where she celebrated the Fourth of July with King George I of Greece and his son and daughter-in-law, Prince Andrew of Greece and Princess Alice of Battenberg. The squadron paid goodwill calls at Corfu, Trieste, and Fiume before returning to Newport, Rhode Island, on 29 August 1904.
Kearsarge remained flagship of the North Atlantic Fleet until relieved 31 March by battleship Maine, but continued operations with the fleet. During target practice off Cape Cruz, Cuba, on 13 April 1906, an accidental ignition of a powder charge of a 13-inch gun killed two officers and eight men. Four men were seriously injured. Attached to the Second Squadron, Fourth Division, she sailed on 16 December 1907 with the "Great White Fleet" of battleships, sent around the world by President of the United States Theodore Roosevelt. She sailed from Hampton Roads around the coasts of South America to the Western seaboard, thence to Hawaii, Australia, New Zealand, the Philippines, and Japan. From there, Kearsarge proceeded to Ceylon, transited the Suez Canal, and visited ports of the Mediterranean Sea, before returning to the eastern seaboard of the United States. Roosevelt reviewed the Fleet as it passed into the Hampton Roads on 22 February 1909, having completed a world cruise of overwhelming success, showing the flag and spreading good will. This dramatic gesture impressed the world with the power of the U.S. Navy.
Kearsarge decommissioned in the Philadelphia Navy Yard on 4 September 1909 for modernization. She recommissioned 23 June 1915 for operations along the Atlantic coast until 17 September when she departed Philadelphia to land a detachment of Marines at Vera Cruz, Mexico. She remained off Vera Cruz from 28 September 1915 to 5 January 1916, then carried the marines to New Orleans, Louisiana, before joining the Atlantic Reserve Fleet 4 February 1916 at Philadelphia. She trained Massachusetts and Maine State Naval Militia until America entered World War I, then trained thousands of armed guard crews as well as naval engineers in waters along the East Coast ranging from Boston, Massachusetts, to Pensacola, Florida. On the evening of 18 August 1918, Kearsarge rescued 26 survivors of Norwegian barque Nordhav which had been sunk by German Submarine U-117. The survivors were landed in Boston.
Kearsarge continued as engineering training ship until 29 May 1919 when she embarked United States Naval Academy midshipmen for training in the West Indies. The midshipmen were debarked at Annapolis, Maryland, on 29 August and Kearsarge proceeded to the Philadelphia Navy Yard, where she decommissioned 10 May 1920 for conversion to a crane ship and a new career. She was given hull classification symbol AB-1 on 5 August 1920.
In place of military trappings, Kearsarge received an immense revolving crane with a rated lifting capacity of 250 tons, as well as hull "blisters," which gave her more stability. The 10,000-ton craneship rendered invaluable service for the next 20 years. One of many accomplishments was the raising of sunken submarine Squalus off the New Hampshire coast. On 6 November 1941 she was renamed Crane Ship No. 1, allowing her illustrious name to be given to an aircraft carrier. But she continued her yeoman service and made many contributions to the American victories of World War II. She handled guns, turrets, armor and other heavy lifts for new battleships such as Indiana and Alabama, new cruisers Savannah and Chicago, and guns on the veteran battleship Pennsylvania.
In 1945 the crane ship was towed to the San Francisco Naval Shipyard where she assisted in the construction of carriers Hornet, Boxer, and Saratoga. She departed the West Coast in 1948 to finish her career in the Boston Naval Shipyard. As Crane Ship No. 1, her name was struck from the Naval Vessel Register 22 June 1955. She was sold for scrapping 9 August 1955.