Born in Ireland he trained as a monk at Iona in Scotland. In 651 when Aiden died Finan was elected 2nd bishop of Lindisfarne. As Adian before him held firmly to the Celtic traditions. He also debated Ronan, an Englishman, about the correct way to calculate the date of Easter.
On Lindisfarne Finan was responsible for the building of a wooden cathedral, the roof of which was thatched with seagrass. Finan sent missionaries to Mercia and to Essex. He was involved with converting the kings Sigebert of Essex and Peada of the Middle Angles to Christianity.
Finan was bishop of Lindisfarne ten years. On the whole, they were successful years. Despite the mounting quarrels over the tension between Roman and Celtic religious practice.
Finan died in 661, and Cuthbert succeeded him as abbot. Bede is the main source for Finan's life.