Following shakedown and practice amphibious assault training on the U.S. West Coast, President Jackson sailed for the South Pacific 1 July 1942, as a unit of Transport Division 2.

Redesignated APA–18 on 1 February 1943, President Jackson continued to transport reinforcement troops and cargo in support of the consolidation of the southern Solomons.

On 30 June, she landed the 172nd U.S. Army Combat Team and two construction battalion companies on Rendova, then transported survivors of USS McCawley (AP-10), torpedoed by a submarine, to Noumea.

Operating with other vessels of task force TF 31, President Jackson landed elements of the 3rd Marine Division at Empress Augusta Bay, Bougainville Island, 1 November.

Seven days later, while en route back to that island with reinforcements, she was hit by a 550-pound (250 kg) bomb, which fortunately did not explode.

She got underway from San Francisco, 14 June and completed two round-trips to Manila before the cessation of hostilities which found her in drydock at Seattle, Washington.

With the outbreak of the Korean War President Jackson reported to the Commander, Amphibious Force, Pacific Fleet for operational control.

Carrying a full load of passengers and cargo for Yokohama, Japan, President Jackson got underway from San Francisco 25 January 1954, returning 23 February.