While en route to shakedown at Bermuda on 6 November 1944, Kline rescued nine survivors from the U.S. Navy K-classblimpK-34, which had been forced down in a storm. Completing her shakedown, Kline cleared Norfolk, Virginia, on 24 December 1944 for World War II service in the Pacific.
Upon arriving at Pearl Harbor, Territory of Hawaii, on 20 January 1945, Kline trained underwater demolition teams until departing on 14 February 1945 for Leyte in the Philippine Islands. Intensive pre-invasion exercises were completed in the Philippines before Kline arrived off Okinawa on 26 March 1945. Kline's underwater demolition team cleared the approaches to the island. After the main invasion force landed on Okinawa on 1 April 1945, Kline remained in the area in support of the Okinawa campaign as radar and antisubmarine warfarepicket. Her guns also assisted in shooting down a Japanese aircraft on 1 April 1945 and helped down another on 6 April 1945.
Kline departed the Okinawa area on 16 April 1945 and for the next six weeks underwent training and repairs. Departing for Borneo on 2 June 1945, Kline provided close fire support during the invasion of Brunei Bay on Borneo on 10 June 1945, and on 24 June 1945 her underwater demolition team gave valuable service during the invasion of Balikpapan.
Following the surrender of Japan and end of World War II on 15 August 1945, Kline departed California for Japan, arriving at Sasebo, Japan, on 20 September 1945 to commence underwater reconnaissance missions. After similar operations at Nagasaki, Japan, she returned to the United States at San Diego, California, on 19 October 1945 to prepare for Operation Magic Carpet—the seaborne postwar repatriation of American serviceman from overseas—service. Kline made one Magic Carpet cruise to Pearl Harbor and returned 110 Pacific veterans to San Diego on 19 November 1945.
On 21 November 1945 Kline departed San Diego for the United States East Coast, arriving at Norfolk on 5 December 1945. On 28 January 1946, Kline arrived at Green Cove Springs, Florida, for inactivation.