John McDonell of Aberchalder was born at Aberchalder LodgeinScotland, a son of Alexander MacDonell of Aberchalder. In 1773, he came to the Mohawk ValleyofNew York with his father and uncles.
When the Treaty of Paris ended the American Revolution in 1783, McDonell settled with other Highlander Loyalists along the St. Lawrence River in Upper Canada. He was appointed to the land board for the Lunenburgh District in 1788 and later for Glengarry & Stormont in 1792. He was appointed to the Court of Common Pleas and the district Court of Quarter Sessions. He was also named lieutenant for Glengarry County in 1792. He played an important role in the local militia, commanding the Upper Canada Battalion of the Royal Canadian Volunteer Regiment.
In 1792, McDonell and his brother Sir Hugh MacDonell of Aberchalder were elected to the Legislative Assembly representing Glengarry. John was chosen speaker. He was reelected in 1796, but was unable to attend until 1798 due to illness.
John McDonell of Aberchalder died of what was described as a "severe cold" at Quebec City in 1809. He was 51 years old and was serving at the time with the 10th Royal Veteran Battalion.
