Lynch was a member of The Tribes of Galway, and served the term 1498-1499.
He is notable in that he attempted to connect the Corrib with Lough Atalia on the east of the town.
In the late 15th and early 16th centuries, Galway was engaged in a trade war with Limerick.
Merchants from the latter city were licensed by letters patent from Edward IV to arrest any inhabitants of Galway found in Limerick and have their good impounded until an owed by Andrew Lynch fitz Stephen was paid.
Andrew is stated in a contemporary document to have died while under arrest in Dublin in March 1523.