"It is not yet a victory because there will be a second round. But this is a stunning outcome of many years of discussions in France about the relationship with its own sovereignty, European integration and the outside world," Chairman of the Federation Council Committee on Foreign Affairs Konstantin Kosachev wrote on Facebook.
The second round of regional elections is scheduled for Sunday, December 13. FN's victory is seen as a launchpad for Le Pen's presidential ambitions in 2017.
The rise of far-right movements across Europe have been attributed to growing public anti-migrant and eurosceptic sentiment within the 28-member bloc. The FN received the second most votes in the departmental elections in March.