Cronyn was born in Kilkenny, Ireland and educated at Trinity College, Dublin.

[1] A member of the prominent Anglo-Irish Protestant Ascendancy Cronyn family, he emigrated to Canada in 1832.

He was posted to London, Ontario, where he completed the church building started by his predecessor.

[citation needed] A noted Low Church cleric, he distrusted what he considered to be the romanizing tendencies of Toronto's Trinity College, in 1863, he founded Huron University College which in 1908 grew into the secularised University of Western Ontario.

He had married in Ireland Margaret Ann Bickerstaff of Lislea, Longford with whom he had seven children.