The victim, identified as 52-year-old Anke H., had been continuing to receive treatment for the injuries she sustained during the attack at a hospital in Germany's Offenbach when she died on Feb. 22.
An Islamic State (IS) militant initially killed 10 foreign nationals and wounded 15 others after blowing himself up near the Obelisk of Theodosius in Sultanahmet Square in the morning hours of Jan.12.
The death toll rose to 11 on Jan. 26, when a 63-year-old victim died at a hospital in Berlin's Marzhan.
The passing of Anke H. has pushed the latest figure on the number of Sultanahmet bombing victims to 12.
Little more than a month after the attack in Istanbul, Turkey was hit by another bomb attack on Feb. 17, this time in the capital Ankara, which killed 28 people and wounded 61 others.