In 563 he traveled to Scotland with twelve companions, where according to his legend he first landed at the southern tip of the Kintyre peninsula, near Southend.:) However, being still in sight of his native land he moved further north up the west coast of Scotland. In 563 he was granted land on the island of Iona off the west coast of Scotland which became the centre of his evangelizing mission to the Picts. However, there is a sense in which he was not leaving his native people, as the Irish Gaels had been colonizing the west coast of Scotland for the previous couple of centuries. Aside from the services he provided guiding the only centre of literacy in the region, his reputation as a holy man led to his role as a diplomat among the tribes; there are also many stories of miracles which he performed during his work to convert the Picts. He visited the pagan king Bridei, king of Fortriu, at his base in Inverness, winning the king's respect. He subsequently played a major role in the politics of the country.

He was also very energetic in his evangelical work, and, in addition to founding several churches in the Hebrides, he worked to turn his monastery at Iona into a school for missionaries. He was a renowned man of letters, having written several hymns and being credited with having transcribed 300 books. One of the few, if not the only, times he left Scotland after his arrival was toward the end of his life, when he returned to Ireland to found the monastery at Durrow. He died on Iona and was buried in the abbey he created.