Following trials at Seattle, Washington, and shakedown off San Pedro, California, Rockingham reported to the U.S. Pacific Fleet 30 December 1944.

On 27 April, Rockingham experienced the first of many enemy air attacks, witnessing the sinking by a suicide Kamikaze plane of nearby SS Canada Victory.

On 1 May Rockingham sent boats to assist USS Terror (CM-5), hit and badly damaged by a suicide plane, taking on board 55 casualties.

After unloading troops on the Tokyo Plain, she proceeded to Leyte and Samar to pick up veterans and returned to San Francisco, 5 November.

She then made another "Operation Magic Carpet" run to the Philippines reaching Los Angeles, California, 23 December.

Remaining on the U.S. West Coast until 11 March, she steamed for Eniwetok and Kwajalein to participate in the Joint Task Force 1 atomic bomb tests.