Originally known as the "Hagia Theodosia" for a woman martyred during a brief, but violent period of the Orthodox iconoclasm in the 8th century, the church gained its new name after a tragic, but poetic, set of events.
On the evening of the final day of the Ottoman siege of Constantinople, legend held that Emperor Constantine XI and Athanasius II (Pattelarus) of Constantinople, the Orthodox Patriarch of the city held their final vigil here, praying for a miracle to deliver them from almost certain death. When the time came for the Emperor to lead his final defense, hundreds of people had remained in the church, adorning it with rose petals and chanting endless prayers for their safety.
The next day, the Ottomans broke through the walls and the city fell. When Sultan Mehmet II's army reached the Hagia Theodosia, they found it littered with rose petals and heavy-hearted citizens. All who had remained were taken prisoner, and the church was converted for general military purposes.
Some two decades later, the Ottomans repaired the structure for use as a place of worship, naming it Rose Mosque in remembrance of its final days as a Christian church.