After shakedown off the West Coast, "Hobby" proceeded to New York City on 12 February 1943, to begin transatlantic convoy duty between there and Casablanca. In five voyages to the Mediterranean Sea that year, "Hobby" developed several U-boat contacts and was credited with inflicting severe damage on one marauder on 9 May. She sailed from Norfolk, Virginia on 2 January 1944 for the Pacific, where she remained in the New Guinea area until 22 August providing fire support and ASW screen for various invasions in the Admiralty and Schouten Islands. Sailing north in the fall, "Hobby" provided fire support for Peleliu and Ngesebus island invasions and then remained on screening duty through November. Despite frequent contacts with Japanese aircraft, she emerged untouched.