St. Nino had a vision where the Virgin Mary gave her a Grapevine Cross and told her to preach in Iberia, the ancient Georgia. Saint Nino reached the borders of ancient Georgian Kingdom of Iberia in about 323 A.D. There, she placed a Christian cross in the small town of Akhalkalaki and started preaching the Christian faith in Urbnis and finally reaching Mtskheta (the capital of Iberia). The Iberian King Mirian III, Queen Nana and whole nation were converted to Christianity, after Nino's preaching and miracles.

In 326 A.D. King Mirian made Christianity as the state religion of his kingdom.

Georgian Church marks St. Nino Day twice a year: on June 1 - the Entrance of St. Nino to Georgia and on January 27 - the day of her passing away.