In March 1944, Monongahela joined the At-Sea-Replenishment Group for Fast Carrier Task Force 58, for the remainder of the war operating continuously with the fast carriers, participating in every major central Pacific operation from the Hollandia, New Guinea, invasion in April 1944 to the invasion of Okinawa a year later. The oiler supported the flattops during the second strikes on Truk, the invasion of the Marianas, the Battle of the Philippine Sea, the Palaus invasion, the Leyte campaign, and the liberation of the Philippines. In November 1944, she was one of those oilers in Capt.
In March 1944, Monongahela joined the At-Sea-Replenishment Group for Fast Carrier Task Force 58, supporting fast carriers throughout the remainder of World War II. She participated in all major Pacific operations from the Hollandia invasion to the Okinawa invasion, including Truk strikes, Marianas invasion, Battle of the Philippine Sea, Palaus invasion, Leyte campaign, and the liberation of the Philippines. In November 1944, she was one of several oilers under Captain's command.