The city was among the most seriously affected by the 2011 Tōhoku earthquake and tsunami. A tsunami about 10 meters high traveled 600 meters inland and destroyed around 80% of the 700 houses in the coastal whaling port of Ayukawa and district of Kadonowaki. Approximately 46% of the city was inundated by the tsunami. One elementary school, Okawa Elementary, was completely destroyed, killing 74 of 108 students and 10 of 13 teachers and staff. As of 17 June 2011, a total of 3,097 deaths had been confirmed in Ishinomaki due to the tsunami, with 2,770 unaccounted for. Approximately 29,000 city residents lost their homes.
The earthquake shifted the city southeast and downward, lowering it by as much as 1.2 m in some areas and causing it to flood twice daily at high tide.