Following a Bermuda shakedown, Oswald sailed north to Boston, Massachusetts, thence to New York City where she reported for duty with CortDiv 22 in TG 21.5.

Off Northern Ireland, on 30 August, she hunted unsuccessfully for an enemy submarine after the loss of the tanker SS Jacksonville.

Rejoining the convoy, the escort vessel saw the remainder of her charges into Derry, and on 4 September began the voyage back to New York.

In June 1945, her task group, then designated 61.2, was dissolved and Oswald reported to Quonset Point, Rhode Island, to serve as plane guard during carrier qualification exercises on Croatan (CVE-25).

Arriving at Green Cove Springs, Florida, on 9 November, she decommissioned there on 30 April 1946 and joined the Atlantic Reserve Fleet.