After fitting out at Puget Sound the ship began service with the Inshore Patrol, 13th Naval District, early in October.

The ship departed Seattle, Washington, on 17 May for a brief visit to San Francisco, California, until 1 June when she got underway for the southwestern Pacific.

Her active service was interrupted only by two repair periods – August and September 1943 at Port Chalmers, New Zealand, and November 1943 to February 1944 at Pearl Harbor.

She spent the ensuing two years engaged in net and other district craft operations in the waters adjacent to the islands of Leyte and Samar.

The ship also performed several assignments off Iwo Jima laying mooring buoys and assisting in the recovery, repair and replacement of submarine lines.

The ship conducted operations at Sasebo and Yokosuka, Japan, until 7 July 1951 when she set sail for Guam to resume her former duties in the Trust Territories.

On 14 December 1957, the Naval Ordnance Test Station (NOTS), China Lake, California, assumed operational control of USS Butternut.

China Lake, however, retained operational control over Butternut for the purpose of testing the Mark 46 anti-submarine warfare (ASW) torpedo and its first modification.