The son of a distinguished Quebec family, Gaspé inherited the family estate on the St. Lawrence River. He received a classical education in Quebec, studied law there, and later became sheriff. Bankruptcy, for which he spent over three years in debtors' prison, forced his withdrawal from public life in his 40s into a quiet life of reading and meditation.

When he was 76 years old, inspired by a rebirth of Canadian nationalism in the mid-19th century, Gaspé wrote Les Anciens Canadiens (The Canadians of Old). A French Canadian classic, it is a romantic historical novel set in Canada at the time of the British conquest (1760). Its idealization of the “good old days,” the farmer's loyalty to the soil, and distrust of English Canada influenced the Canadian regionalist school of literature that flourished into the 1930s. In 1866 Gaspé published Mémoires (1866; Eng. trans. A Man of Sentiment: The Memoirs of Philippe-Joseph Aubert de Gaspé, 1786–1871), a lively portrait of his life and times. He is also thought to have contributed to the first French Canadian novel, L'Influence d'un livre (1837; The Influence of a Book), by Philippe-Ignace-François Aubert de Gaspé, his son.