John McCloy was born on 30 January 1876 in Brewster, New York. He enlisted from that same state in the U.S. Navy in March 1898 and reported on board USS Columbia. Remaining at sea, he served in succession on board USS Monterey, the schooner Manila,the gunboats Gardoqui and Arayat, and the cruiser Newark. In June 1900, while on board Newark, McCloy was a Coxswain during the China Relief Expedition and participated in the landing force at Peking, China. On 13, 20, 21, and 22 June, he distinguished himself in battle against the enemy. For his "meritorious conduct," he was awarded the Medal of Honor. In April 1901, McCloy renlisted and reported on board the schooner Manila. Following a tour in the Caribbean on board the gunboat Alliance, he was appointed as a Boatswain and assigned to the cruiser Atlanta. In 1905, he reported to USS Galveston and was on board when she participated to escort the remains of John Paul Jones back to the United States. Remaining at sea, McCloy served on the ships USS Hancock then the receiving ship Franklin. On 30 Jul 1909, he was appointed to warrant officer rank of Chief Boatswain and transferred for duty on board the collier Lebanon. In June 1911, he was assigned to the Naval Station at Key West, Florida.

In September 1913, McCloy returned to sea on board USS Florida and participated as Beach Master for the landing force in the occupation at Vera Cruz, Mexico. On 21-22 April 1914, while leading three picket launches admist heavy enemy fire, McCloy was wounded but remained on his post, enabling cruisers to save American lives. For his gallant heroism, he was awarded his second Medal of Honor. He recuperated from his injuries at the New York Naval Hospital and returned to sea duty on board USS Tennesseee followed by a tour of duty on board USS Maine. In late 1916, he served as the Assistant to the Captain of the Yard at the Boston Navy Yard in Massachusetts. During World War I, McCloy accepted a temporary commission to Ensign in the summer of 1917 and commanded the seagoing tug Ontario. In early 1918, he commanded the tug Favorite and was temporarily promoted to Lieutenant that June.

Following World War I, McCloy assumed commanded of the newly commissioned minesweeper Curlew in January 1919 and cleared mines from the North Sea. In August 1920, he was permanently promoted to Lieutenant. At the start of the new year, he transferred to command the minesweeper Comorant. Returning to shore duty in February 1922, he served at the New York Navy Yard, assisting the Third Naval District. In November 1923, he assumed command of the minesweeper Lark, transferring for duty on board USS Patoka then to the newly commissioned USS Memphis. After a short stay at the Naval Hospital at League Island, Philadelphia, Pennsylvania, McCloy served on the destroyer tender Dobbin. In July 1927, he reported back to the New York Navy Yard. He retired in October 1928 and was placed on the retired list. For his prior combat service, McCloy was promoted to Lieutenant Commander in April 1942. John McCloy died on 24 May 1945 and is buried in Arlington National Cemetery, Arlington, Virginia.