Theodora was the wife of Emperor Theophilus the Iconoclast, but secretly revered the icons, and protected others who did, until the emperor's death. Upon his death, she quickly restored veneration of icons to churches throughout the empire, the event celebrated on the upcoming Sunday of Orthodoxy, the first Sunday of the Great Fast. She ruled wisely as regent for the young emperor Michael for fifteen years: she is said to have initiated the mission of Sts Cyril and Methodios to the Slavs. Before Michael III reached his majority, he was prevailed upon by Bardas, Theodora's brother, to depose her and send her to a monastery, where she finished her life in peace and holiness.

When Constantinople fell, her incorrupt relics were taken to Corfu along with those of St Spyridon. They are still venerated there.

There is a much-debated story that, when Theophilus was dying, the Empress, moved by compassion for him, brought an icon of the Mother of God out of hiding and laid it on his face; and that Theophilus, coming to himself, kissed the holy icon and confessed the true Faith before giving up his soul. Other accounts say that the Emperor died in heresy. It seems possible that the holy Empress circulated the story to ensure that her departed husband would be remembered in the Church's prayers.