He attended the school of Lycée Louis-le-Grand for secondary preparatory education for entrance to the famous École Polytechnique.

In October 1794, at age 17, he took the École Polytechnique entrance exam and failed the algebra section but was still accepted.

A student there for two years, he left in 1797 to study at École des Ponts et Chaussées to become a civil engineer.

Although now on course for the practical and secure professional study of civil engineering, he discovered his true passion, abstract mathematics.

Poinsot thus left the École des Ponts et Chaussées and civil engineering to become a mathematics teacher at the secondary school Lycée Bonaparte in Paris, from 1804 to 1809.

By 1812 Poinsot was no longer directly teaching at École Polytechnique using substitute teacher Reynaud, and later Cauchy, and lost his post in 1816 when they re-organized, but he did become admissions examiner and held that for another 10 years.

On the death of Joseph-Louis Lagrange in 1813, Poinsot was elected to fill his place at the Académie des Sciences.

moves in a plane perpendicular to the angular momentum (in absolute space) of the rigid body.