Unruffled spent most of her eventful wartime career in the Mediterranean, where she sank the Vichy-French merchant Liberia (the former Greek Cape Corso), the Italian auxiliary minesweeper N 10 / Aquila, the Italian merchants Leonardo Palomba, Una, Sant'Antioco, Citta di Catania, and Città di Spezia, the Italian tankers Castelverde and Teodolinda, the Italian sailing vessel Amabile Carolina, the Italian naval auxiliary Z 90 / Redentore, the German merchants Lisboa, Pommern and Baalbeck and the French tanker Henri Desprez. Unruffled also torpedoed and sank the Italian merchant Loreto. She was carrying prisoners of war, 130 of whom were lost.
She also launched failed attacks on the Italian submarine Antonio Sciesa and the small German minesweeper R 212, but her most important target was the Italian light cruiser Attilio Regolo, which was torpedoed by Unruffled on 7 November, 1942. 60 feet of bow were blown off, but Unruffled could not sink the cruiser, having by now run out of torpedoes. The damaged cruiser was towed to port by the tug Polifemo, escorted by the torpedo boats Cigno, Lince and Abba. Another attack by HMS United failed, but the Attilio Regolo was out of action for the rest of the war.
Unruffled survived the war and was scrapped at Troon in January 1946.