In 1716, Thornton's family immigrated to North America when he was three years old, settling first in Wiscasset, Maine.

[5] James and Elizabeth Thornton fled from their burning home with Matthew, moving shortly thereafter to Worcester, Massachusetts.

[5] Thornton became a Londonderry selectman, a representative to and president of the Provincial Assembly, and a member of the Committee of Safety, drafting New Hampshire's plan of government after dissolution of the royal government, which was the first state constitution adopted after the start of hostilities with England.

He retired from his medical practice, and in 1780, moved to Merrimack, New Hampshire, where he farmed and operated Thornton's ferry with his family.

Thornton's residence in Derry, which was part of Londonderry at the time, is listed on the National Register of Historic Places.

Matthew Thornton, a suspected Loyalist who was charged with treason related to actions just before the Battle of Bennington in 1777.