In company with "I-121", "I-122" departed Davao on 9 February 1942 to begin her third war patrol, with a primary mission of supporting an impending air attack on Port Darwin by planes from the aircraft carriers of Vice Admiral Chuichi Nagumo′s Mobile Force and land-based aircraft from both Ambon and Kendari, Celebes. She parted company with "I-121" on 13 February 1942; while "I-121" headed south, "I-122" proceeded southeast to patrol west of the Torres Strait, where she had orders to attack Allied shipping as well as serve as a picket to watch for Allied ship movements. On 19 February 1942 at 09:57, 188 aircraft from Nagumo's carriers began an attack on Darwin's harbor, airfields, and urban center, followed by a raid by 55 Japanese land-based bombers. The attack sank eight ships, damaged nine ships, destroyed 15 aircraft, and damaged structures in the city itself.