Gudin was born to a noble family in Montargis, on 13 February 1768. After studying at the military school of Brienne, in October 1782 he joined the King's Guard as a gendarme. In September 1784 he entered the Régiment d'Artois with the rank of sub-lieutenant, and between January 1791 and January 1793 was stationed in the Saint-Domingue garrison as a lieutenant. Gudin was appointed to several positions as a general staff officer in the Army of the North, then of the Rhine and Moselle. He became a brigade general at the beginning of 1799 and was given a command during the Swiss campaign. The following year he took part in the battles of Stein, Stockach, Messkirch, Memmingen, Höchstädt and Neuburg. Promoted to general of division for his valor on the battlefield, on 11 July 1800 he took Füssen. That winter he commanded the 2nd division in the right wing under Lecourbe at the decisive French victory at Hohenlinden.