He was born at Aix in Provence. His father was a locksmith from the Vendée, who enthusiastically accepted the principles of the French Revolution and encouraged liberal ideas in his son. François had brilliant success at Avignon in the lycée where he was afterwards professor (1815); he returned to Aix to study law, and in 1818 was called to the bar, where his eloquence would have ensured his success had he not been more interested in the study of history. His abilities were shown in an Eloge de Charles VII, which was crowned by the Académie de Nîmes in 1820, and a memoir on Les Institutions de Saint Louis, which in 1821 was crowned by the Academie des Inscriptions et Belles Lettres.
He then went to Paris, where he was soon joined by his friend and compatriot, Adolphe Thiers, the future president of the French republic. He was introduced by JA Manuel, formerly a member of the Convention, to the Liberal paper, Courrier francais, where he became a member of the staff which carried on a fierce pen-and-ink warfare against the Restoration. He acquired his knowledge of the men and intrigues of the Napoleonic epoch from Talleyrand.
Mignet's Histoire de la revolution française (1824), in support of the Liberal cause, was an enlarged sketch, prepared in four months, in which more stress was laid on fundamental theories than on the facts. In 1830 he founded the National with Thiers and Armand Carrel, and signed the journalists' protest against the Ordonnances de juillet, but he refused to profit from his party's victory. He was satisfied with the modest position of director of the archives at the Foreign Office, where he stayed till the revolution of 1848, when he was dismissed, and retired permanently into private life. He had been elected a member of the Académie des Sciences Morales et Politiques, re-established in 1832, and in 1837 was made the permanent secretary; he was also elected a member of the Académie française in 1836, and sought no further honours.
He was well known in fashionable circles, where his witty conversation and pleasant manners made him a favourite. Most of his time was devoted to study and to his academic duties. Eulogies on his deceased fellow-members, the Academy reports on its work and on the prizes awarded by it, which it was part of Mignet's duty as secretary to draw up, were thoroughly appreciated by connoisseurs, and were collected in Mignet's Notices et portraits.
He worked slowly and lingered over research. With the exception of his description of the French Revolution, which was chiefly a political manifesto, all his early works refer to the middle ages--De La feodalite, des institutions de Saint Louis et de l'infiuence de la legislation de ce prince (1822); La Germanie au viii' et an ix' siècle, sa conversion an christianisme, et son introduction dens la société civilisée de l'Europe occidentale (1834); Essai sur la formation territoriale et politique de la France depuis la fin du xi' siècle jusqu'd la fin du xv (1836); all of these are rough sketches showing only the outlines of the subject.
His most famous works are devoted to modern history. For a long time he had been taken up with a history of the Reformation, but only one part of it, dealing with the Reformation at Geneva, was published. His Histoire de Marie Stuart (2 vols., 1851) made use of some previously unpublished documents, mostly taken from the archives of Simancas. He devoted some volumes to a history of Spain, which had a well-deserved success--Charles Quint, son abdication, son sejour, et sa mort au monastère de Yuste (1845); Antonio Perez et Philippe II. (1845); and Histoire de la rivalité de François I et de Charles Quint (1875). At the same time he had been commissioned to publish the diplomatic acts relating to the War of the Spanish Succession for the Collection des documents inédits; only four volumes of these Negociations were published (1835-1842), and they do not go further than the peace of Nijmwegen; but the introduction is celebrated, and Mignet reprinted it in his Mélanges historiques.
He died at Paris. See the eulogy of Mignet by Victor Duruy, delivered on entering the Académie Française on June 18 1885, and the notice by Jules Simon, read before the Académie des Sciences Morales et Politiques on November 7 1885. This entry was originally from the 1911 Encyclopedia Britannica.