Signet arrived off Iwo Jima on 16 February, three days prior to the assault. The minesweeper remained in the vicinity of Iwo Jima until 7 March. During the intervening period, she swept mines and screened the transports, particularly during the nightly retirements from action. Her crew rescued a downed American flier during evening of 21 February and watched the U.S. Marines hoist the colors on the summit of Mount Suribachi on the 23d. On 4 March, Signet's crew began to understand the significance of Iwo Jima as they watched the first crippled B-29 land on its airfield. On 7 March after a little more than three weeks of sweeping, patrolling, and being harassed by enemy planes Signet cleared Iwo Jima for Ulithi Atoll in the Carolines.