Muin-i Zafer, which means “Aid to Victory” in Ottoman Turkish, was ordered in 1867 from the Samuda Brothers shipyard in London, with construction beginning in 1868 and the ship's launch taking place in June 1869. After conducting sea trials in 1870, it was commissioned into the Ottoman fleet. During its early years of service, the ship, along with other Ottoman ironclads, was deployed to Crete to help stabilize the island in the aftermath of the Cretan Revolt of 1866–1869.
However, it was during the Russo-Turkish War of 1877–1878 that Muin-i Zafer truly made its mark. Operating as part of the Black Sea squadron, the ship, under the command of Hobart Pasha, played a crucial role in supporting Ottoman forces in the Caucasus. It bombarded Russian positions and captured the Black Sea port of Sokhumi in May 1877. The Ottoman fleet's presence forced the Russians to allocate resources for coastal defense, but the Ottoman high command failed to exploit its naval superiority fully.
Following the Russo-Turkish War, Muin-i Zafer was laid up in Istanbul and saw little activity for the next two decades. In 1882, minor upgrades were made to the ship's armament, including the addition of two 87 mm breech-loading guns manufactured by Krupp. However, poor maintenance and neglect plagued the entire Ottoman ironclad fleet during this period.
By 1906, the ship underwent a significant transformation. Its old muzzle-loading guns were replaced with new 150 mm Krupp 40-caliber guns, and a new light battery was added, including six 75 mm quick-firing Krupp guns. Despite these updates, the Muin-i Zafer's overall condition continued to deteriorate.
As the First Balkan War began in 1912, Muin-i Zafer had been stationed back in Izmir. It eventually found new roles, serving as a torpedo training ship in 1913, a floating barracks in 1920, and a depot ship for submarines in 1928. However, its long and storied career ultimately came to an end in 1932 when it was decommissioned. The ship was finally broken up for scrap in 1934.