Jo Swinson has pledged to lead a movement that will take on nationalism and populism, attacking violence and division sparked by the Scottish independence and Brexit campaigns as she was named the leader of the Liberal Democrats.
Ms Swinson claimed victory by a wide margin, beating her rival Sir Ed Davey by 47,997 votes to 28,021.
The East Dunbartonshire MP said she was a candidate for Prime Minister and pledged to “lead and grow the bigger, open, liberal movement that our country so desperately needs.”
Ms Swinson, who takes over from Sir Vince Cable a day before the next leader of the Conservative Party is named, said “Britain deserves better than Boris Johnson”.
Recommitting the Lib Dems to stopping Brexit, she also took on the SNP, linking the 2014 independence campaign to the divisions caused by the 2016 EU referendum.
“Scotland’s independence referendum heralded a new politics, and not in a good way,” Ms Swinson said.
“Sandra, one of my local members, had a brick thrown through her window, which displayed a pro-UK poster. On the campaign trail, an elderly woman pulled up her coat sleeve to show the pro-UK campaign sticker on the inside of her wrist – such was her fear of wearing it on her jacket.
“A mob of hundreds outside the BBC, demanding Nick Robinson be sacked. Twitter trolls, fake news, demonising journalists, we saw it in Scotland first.
“And since then, that harsh, hostile politics has become the new normal.”
The Lib Dem leader attacked Nigel Farage for saying that Brexit had been won “without a bullet being fired”, eight days after the Labour MP Jo Cox was murdered.
“Crass, insensitive. Farage just didn’t care,” she said.
Ms Swinson added: “It feels like our liberal values are under attack.
“We champion freedom – but Brexit will mean the next generation is less free to live, work and love across Europe.
“We value openness – but Britain is in retreat, pulling up the drawbridge.
“We cherish equality, so that every individual can thrive: whoever they are, whatever their background, however they worship.
“But this is threatened too – that shocking picture of those gay women, bloodied, attacked on a bus. And the rise in Islamophobia and anti-Semitism, in the heart of British politics.”
The SNP immediately hit back, demanding that Ms Swinson apologise for the austerity measures imposed by the coalition government, and rule out a future pact with the Conservatives.
“Jo Swinson was one of the most enthusiastic cheerleaders for the Tory coalition government,” SNP MP Mhairi Black said.
“She must move quickly to apologise for the devastating cuts she imposed, and rule out any future Tory pact - if she wants anyone to believe the Lib Dems have changed their ways.”
Scottish Liberal Democrat leader Willie Rennie said Swinson would attract new voters to the party and “take the Liberal Democrats to greater heights”.
"Jo provides a stark contrast between the indecisive Jeremy Corbyn and chaotic Boris Johnson and will lead the country away from the forces of populism and nationalism,” Mr Rennie said.