Le Pen, the out-going president and only candidate for election, was unsurprisingly confirmed at the head of the far-right National Rally for a fourth mandate at the party congress in the southern French city of Perpignan.
Marine Le Pen is seeking new impetus for her 2022 presidential bid after performing poorly in last month's regional polls.
The National Rally (RN), which had been tipped for strong gains in the regional elections, was left floundering after failing to win any of the 13 regions in mainland France.
The results raised questions about Le Pen's strategy of trying to detoxify her party's brand and position it as a more mainstream right-wing force.
But she faced no challenge for the party leadership, with her quest for a fourth term winning the backing of over 98 percent of members in an online and postal ballot.
The result was announced on the second day of the National Rally's congress in the southern city of Perpignan.
In a sign that the party is broadly supportive of Marine Le Pen's strategy of softening the party's image, one of her protegés, Jordan Bardella, was chosen on Sunday to stand in for her as party leader during the presidential campaign.
Bardella, a media-savvy 25-year-old who flopped in the regional elections in the greater Paris region, is currently the RN's deputy leader.
A keynote address to rally the faithful
The 52-year-old lawyer is expected to use a keynote address later this Sunday to "rally the troops" ahead of the presidential vote next year.
Polls show the election coming down to another duel between Le Pen and centrist President Emmanuel Macron, who defeated the anti-immigration candidate handily in the second round of the 2017 election.
But that scenario is no longer a foregone conclusion.
Macron is also seen as being weakened by the poor performance of his Republic on the Move (LREM) party in the regional election.
LREM, which was founded in 2016, finished last of the big parties, winning just 7 percent of second-round votes in an election characterised by record low turnout.