Jordan Bardella succeeded his mentor Marine Le Pen on Saturday at the helm of France's most popular far-right party, National Rally.
Bardella, 27, won an internal party vote with 85% support, marking a symbolic change of the guard at the resurgent anti-immigration party.
He is the first person to lead the party who does not come from the Le Pen family since it was founded a half-century ago.
Bardella pledged to protect France from perceived threats posed by immigration and defended a party member who made a racist remark in parliament earlier this week.
The National Rally is seeking to capitalise on its recent breakthrough in France's legislative election and growing support for far-right parties in Europe, notably in neighbouring Italy.
It is also facing broad public anger over an offensive comment by one of its members in parliament in response to a black lawmaker.
Marine Le Pen is still expected to wield significant power in the party's leadership and run again for France's presidency in 2027.
She said she stepped aside to focus on leading the party's 89 lawmakers in France's National Assembly.
To broad applause, she hugged Bardella after the results were announced at a party congress on Paris' Left Bank, and both raised their arms in victory.
Le Pen said Bardella's main challenge would be pursuing the party "roadmap" of taking power in France.
"We are going to win!" supporters chanted.
New party leader asks for 'drastic' immigration rules
Anti-racism activists, union leaders and politicians protested nearby Saturday against the National Rally, denouncing what many see as a creeping acceptance of its xenophobic views.
Yeliz Alkac, 30, said that she was demonstrating to support people who face persistent racism in France.
She described shock that the remark in parliament denigrating African immigrants was seen as "normal" by some in France.
"The fact that the National Rally has 89 lawmakers at the National Assembly is a strong signal. It should be a warning about how the extreme right is going strong," she said.
In his speech Saturday, Bardella defended the National Rally legislator who was suspended over the remark, calling him a victim of a "manhunt".
Bardella described his family's Italian immigrant roots and pride at becoming French but made it clear that not all foreigners are welcome.
"France shouldn't be the world's hotel," he said, calling for "drastic" limits on immigration.
He welcomed a representative of Italian Premier Giorgia Meloni's far-right party who came to the congress, calling for a "rapprochement" of similar forces in Europe.
Bardella had been the interim president of the National Rally since Le Pen entered the presidential race last year.
He beat out party heavyweight Louis Aliot, 53, who had argued that the National Rally needs to reshape itself to be more palatable to the mainstream right.
"Bardella's election feels like a fresh push," said party member Marie Audinette, 23. "He embodies the youth."
Audinette, who grew up in a working-class neighbourhood in Bordeaux, said that her country "was perishing," citing deteriorating public services that struggled to cope with the COVID-19 pandemic.
She also described "a clear change of population" in Bordeaux.
Some far-right supporters in France increasingly refer to the false "great replacement" conspiracy theory that the populations of Western countries are intentionally being overrun by non-white, non-Christian immigrants.
The claim, propagated by white supremacists, has inspired deadly attacks.
Questions remain over Le Pen's Moscow connections
Le Pen lost to French President Emmanuel Macron on her third presidential bid in April but earned her highest score yet.
Two months later, her party won its most seats to date in the lower house of parliament, in part thanks to Le Pen's efforts to focus on inflation and workers' economic troubles.
Le Pen has worked to remove the stigma of racism and antisemitism that clung to her party and broaden its base.
She has notably distanced herself from her now-ostracised father, Jean-Marie Le Pen, who co-founded the party then called the National Front and has been repeatedly convicted for hate speech.
"Bardella is part of a generation of young, very young, people who engaged themselves behind Marine Le Pen in the 2010s and who probably wouldn't have joined the National Rally during Jean-Marie Le Pen's era," political scientist Jean-Yves Camus said.
The Le Pen family and the party also have deep ties to Vladimir Putin's Russia.
While Le Pen condemned Russia's invasion of Ukraine, she has also questioned the Western sanctions against Russia, and her party took out a €9.01-million loan from the First Czech-Russian bank in 2014 that many see as a Russian effort to influence French politics.
According to Camus, Saturday's party vote won't question Le Pen's leadership.
"Le Pen won't have to deal with the party (now) and can focus on the most important thing, leading the party's lawmakers in the National Assembly," he said.