The son of a paper mill owner, Gabriel-Julien Ouvrard received a basic education, joining a trading house in Nantes in 1787 as an employee.
It was also associated with three major suppliers: Vanlerberghe (wheat), the Michel brothers (military supplies) and Carvillon des Tillières et Roy (steel and wood).
A few months later, he won a contract with the Spanish fleet stationed in Brest and then one to supply the army of Italy in 1799.
Ouvrard was arrested on 27 January 1800 on the orders of then First Consul Napoleon Bonaparte, but a review of his accounts and contracts showed no irregularities.
Ouvrard was one of the founders of the Compagnie des Négociants Réunis along with the banker Médard Desprez (1764–1842), Regent of the Bank of France.
In exchange for a cash advance, the company received valid obligations including monthly subsidies that Spain had to pay to France in implementing the Treaty of 22 June 1803.
In 1805 the Bank of France faced collapse; this potential financial disaster was averted on 27 January 1806, when Ouvrard agreed to guarantee loans against the gold from the Spanish South America colonies.
Ouvrard played a large role in the economic recovery of France after the fall of the Empire.
The following year, the purveyor financed the shipment of Spain, but was never repaid in spite of agreements signed with the Duke of Angoulême, who commanded the expedition.