He was born at Maureilhan, near Béziers, in the départment of Hérault. At fifteen he began studying medicine at Montpellier, where in 1823 he received the degree of doctor. In the following year he went to Paris, carrying an introduction from AP de Candolle, the botanist, to Georges Cuvier, who received him kindly, and took an interest in him. At Paris Flourens engaged in physiological research, occasionally contributing to publications; and in 1821, at the Athénée, he gave a course of lectures on the physiological theory of the sensations, which attracted much attention amongst men of science. His paper entitled Recherches experimentales sur les propriétés et les fonctions du système nerveux dons les animaux vertébrés, in which he, from experimental evidence, sought to assign their special functions to the cerebrum, corpora quadrigemina and cerebellum, was the subject of a highly commendatory report by Cuvier, adopted by the French Academy of Sciences in 1822.
Flourens was chosen by Cuvier in 1828 to deliver a course of lectures on natural history at the College de France, and in the same year became, in succession to LAG Bosc, a member of the Institute, in the division "Economic rurale.” In 1830 he became Cuvier's substitute as lecturer on human anatomy at the Jardin du Roi, and in 1832 was elected to the post of titular professor, which he vacated for the professorship of comparative anatomy created for him at the museum of the Jardin the same year. In 1833 Flourens, in accordance with the dying request of Cuvier, was appointed a perpetual secretary of the Academy of Sciences; and in 1838 he was returned as a deputy for the arrondissement of Béziers. In 1840 he was elected, in preference to Victor Hugo, to succeed JF Michaud at the French Academy; and in 1845 he was created a commander of the legion of honour, and in the next year a peer of France.
In March 1847 Flourens drew the attention of the Academy of Sciences to the anaesthetic effect of chloroform on animals. On the revolution of 1848 he withdrew completely from political life; and in 1855 he accepted the professorship of natural history at the College de France. He died at Montgeron, near Paris.
Besides numerous shorter scientific memoirs, Flourens published: