The son of a poor Parisian servant, Augereau turned to a military career at the age of 17, served in several foreign armies, and returned to France in 1792. He quickly advanced in rank and by 1793 was general of a division stationed in the eastern Pyrenees. In 1795 his division served in the Italian campaign, and his victory at Castiglione (August 5, 1796) convinced Napoleon of his indispensability. He carried out the coup d'état of 18 Fructidor (September 4, 1797) and was elected a deputy and secretary of the Assembly in 1799. Augereau opposed Napoleon's coup d'état of 18 Brumaire (November 9, 1799) and was consequently given unimportant commands from 1800 to 1805. Yet he was appointed a marshal of France in 1804.

In 1806 Augereau commanded a corps at the Battle of Jena. At the Battle of Eylau (February 7–8, 1807), his corps, misdirected in a snowstorm, lost half its numbers. Nevertheless, in 1808 Napoleon named him duc de Castiglione and gave him a new command in Catalonia, in Spain, where he was soon defeated. Recalled to France in 1810, he was given only a minor post during Napoleon's invasion of Russia in 1812. He continued fighting in Germany the following year, but after the losses at the Battle of Leipzig (October 16–19, 1813) he returned to France.

Augereau had grown weary of the war by 1810. After another defeat at Lyon, in 1814, he bitterly attacked Napoleon and declared himself a royalist after the First Restoration of the Bourbon monarchy (1814). Louis XVIII rewarded Augereau for his anti-Napoleonic sentiments, and when he again offered his services to Napoleon in 1815, he was ignored. After the Battle of Waterloo the king gave him no command, and he retired to his estate at La Houssaye.