After a brief stop at Leyte, Bull reached Ulithi to prepare for the invasion of Iwo Jima. On 10 February 1945, she cleared the Carolines as part of TG 52.4, the Underwater Demolition Group of the Amphibious Support Force, Task Force 52 (TF 52). She headed, via Saipan, to Iwo Jima and arrived there three days before the landing. "Bull" took part in the reconnaissance of both preferred and alternate beaches and drew Japanese fire several times, yet she escaped without damage on each occasion, despite several near misses. After "D day", "Bull" operated as a screening vessel, while her embarked UDT cleared beaches to facilitate the landing of supplies. Although the ship's company suffered no casualties, one of UDT-14's officers was killed when a Japanese shore battery sank the LCI in which he had embarked for gunfire spotting.