The next two years were spent in Formula Renault, with finishes in fourth (the highest-finishing rookie that year) and sixth (despite missing half the season with multiple fractures obtained in an accident at Le Mans) respectively, before transferring up to French Formula Three in 1997 with the La Filière Martini team, debuting with another fourth place championship finish.

He consistently outpaced long-time teammate Sébastien Bourdais and ended the season with 10 wins from 22 races, including 12 pole positions, finishing the championship as runner-up behind David Saelens.

A repeat of his unsuccessful year in Formula 3000 prompted a move to World Series by Nissan in 2001, signing for the Epsilon by Graff team.

Montagny returned to the World Series by Nissan in 2003 with Gabord Competicion, and secured his second championship title with nine victories, ahead of Heikki Kovalainen.

He did not finish his second race 2006 Spanish Grand Prix: after a great start, enabling him to gain 3 positions, he retired on lap 10 with a mechanical failure.

Montagny competed in the final Champ Car World Series race, held at the Long Beach circuit on April 20, 2008.

In June, he drove the Peugeot 908 HDi FAP at the 2008 24 Hours of Le Mans and finished in the third place with Ricardo Zonta and Christian Klien.

Montagny made his debut in the American Le Mans Series with Andretti Green Racing at the 2008 Northeast Grand Prix at Lime Rock Park in July 2008, driving an Acura ARX-01B.

[4] He made his IndyCar Series debut in 2009 at the Indy Grand Prix of Sonoma at Infineon Raceway with Andretti Green Racing.