He was born in Inverness-shire, Scotland, the son of Allan McDonell and brother of Alexander Macdonell, and came to the estate of William Johnson in the Mohawk Valley of New York in 1773 as part of a large emigration by members of the MacDonell clan.
He left that area at the beginning of the American Revolution and was educated in Montreal and Quebec City. He became first clerk of the Legislative Assembly of Upper Canada in 1792 and an attorney in 1794. He introduced the Assessment Acting of 1803 which was intended to provide more equal rates.
The ship sank in a storm on Lake Ontario near Brighton with all hands lost.
In October 1804, he was en route to a trial aboard the HMS Speedy where he would defend a native person charged with murder.
He was also a founding member of the Law Society of Upper Canada and its third treasurer.
