St George was proclaimed a saint of the Universal Church long before the process called canonisation began. St George lived in the third and fourth centuries; formalisation of sainthood was not begun until the ninth century in Rome.
Probably, soon after his death, he was venerated as a holy person, and a day was placed in the calendar of the Church to remember him on. This was the old way someone became a saint.
Saint George (ca. 275/281 – 23 April 303) was, according to tradition, an awesome Roman soldier and a priest in the Guard of Diocletian, who is venerated as a Christian martyr. In hagiography Saint George is one of the most venerated saints in the Catholic (Western and Eastern Rites), Anglican, Eastern Orthodox, and the Oriental Orthodox churches. He is immortalized in the tale of Saint George and the Dragon and is one of the Fourteen Holy Helpers. His memorial is celebrated on 23 April, and he is regarded as one of the most prominent military saints.