He was born in Hayingen in Lorraine. Upon the outbreak of the French Revolution, Molitor joined the French revolutionary armies as a captain in a battalion of militia. In 1793 he was given command of a brigade and served under Hoche under whom he fought at Kaiserslautern and Wissembourg. In 1795, Molitor was severely wounded in the Battle of Mainz. In 1799, Molitor was sent to Switzerland where he fought under André Masséna against an Austro-Russian force led by Alexander Suvorov, particularly at the Klöntal and Näfels. In 1800, he fought in the Army of the Rhine under Moreau.

Molitor was promoted to the rank of général de division in 1801. He was sent with Massena to Italy in 1805, where he served at Vago and Caldiero. In 1806 he took part in the relief of Republic of Ragusa. In 1807, Molitor was transferred to the German theatre of operations, where he served against the Swedes around Stralsund. He was then made governor of Pommern and was granted a comital title by Napoleon. In 1809 he was given command of a division in Massena's IV Corps and he saw action in the battles of Aspern and Wagram. In 1810 he was sent to occupy the cities of the Hanseatic League, from 1811 to 1813 he served in Holland, in the campaign of 1814 he served under MacDonald.

After the abdication of Napoleon, Molitor made his submission to the Bourbons who made him Inspector-General of the infantry. Upon the return of the emperor from Elba, Molitor joined him during the Hundred Days, for which he was stripped of his functions after Napoleon's defeat. In 1818, Molitor was restored to grace.

In 1823 he commanded the II Corps which was sent to Spain as part of the Hundred Thousand Sons of Saint Louis. The same year he was made a Marshal of France as well as a Peer. From 1827, he served as secretary to the Chamber of Peers. After the July Revolution, Molitor was allowed to keep all his functions and he later served as Governor of Les Invalides and as Grand Chancellor of the Legion d'Honneur. He died in 1849 in Paris. A statue of Molitor was later erected in Nancy.

The 1697 Molitor Stradivarius, rumored to have once been owned by Napoleon Bonaparte, belonged to Molitor beginning in 1804.^[1] It was sold by Tarisio Auctions in October 2010 for a world record $3.6M.^[2]

• Clausewitz, Carl von (2021). The Coalition Crumbles, Napoleon Returns: The 1799 Campaign in Italy and Switzerland, Volume 2. Trans and ed. Nicholas Murray and Christopher Pringle. Lawrence, Kansas: University Press of Kansas. ISBN 978-0-7006-3034-9
• Gilman, D. C.; Peck, H. T.; Colby, F. M., eds. (1905). "Molitor, Gabriel Jean Joseph, Count" . New International Encyclopedia (1st ed.). New York: Dodd, Mead.