Ontonagon, ex MC hull 1799, was laid down 10 May 1944 by the East Coast Ship Yard Inc., Bayonne, New Jersey; launched 30 June 1944; sponsored by Mrs. Riva Halpern; and commissioned 21 September 1944.

Following shakedown in Chesapeake Bay, Ontonagon cleared Norfolk, Virginia, for the Caribbean, whence, after taking on a petroleum cargo, she continued on to the Pacific Ocean.

Assigned to ServRon 8 until the spring of 1945, she assisted in the first stages of transporting and distributing gasolines to the fleet and to forward bases from the U.S. West Coast.

Returned to the west coast in September, she was placed out of service and transferred to the Maritime Administration, at Olympia, Washington, 14 December 1954.

Struck from the Navy List 22 June 1955, she remained a unit of the National Defense Reserve Fleet.