He was born in Montreal, the son of Joseph Frobisher, and studied in England.
He later worked as a clerk for a merchant in the fur trade at Quebec City.
Frobisher represented Montreal County in the Legislative Assembly of Lower Canada from 1804 to 1808.
In 1815, he was named provincial aide-de-camp for colonial administrator Sir Gordon Drummond and, in 1816, for Governor Sir John Coape Sherbrooke.
After his death his widow and their only son went to live in England at Barton House, Dawlish, the home of her aunt, the widow of Admiral John Schank, and two of Mrs Frobisher's uncles, Sir William Grant, of Beldorney Castle, and Major John Grant (1766-1837).