The 39-year-old won approximately 62% of the overall vote in a leadership contest against parliamentary veteran Sir Ed Davey.
Ms Swinson was the deputy leader of the party, serving under Sir Vince Cable for two years.
The MP was first elected to Parliament in 2005 as the member for East Dunbartonshire.
Entering Parliament at just 25 years old, she was the youngest member in the House of Commons, given the unofficial title of ‘baby of the house’ until 2009.
In the 2015 elections, she lost her seat to the SNP’s John Nicolson, only to win it back during the 2017 snap election.
In 2018, she became the first MP to bring their baby into the Commons during a debate.
She cradled her baby Gabriel while listening to the closing remarks of a discussion about proxy voting, which could allow MPs on maternity and paternity leave to nominate a colleague to cast their vote in their absence.
- Where does she stand on Brexit?
She has been outspoken in backing a second referendum, and made Brexit a focal point in her victory speech, stating: “I will do whatever it takes to stop Brexit.
“Tomorrow, Boris Johnson is likely to take the keys to Number 10 and set us on a path to a damaging no-deal Brexit.
“Stopping Boris, and stopping Brexit is my number one priority as leader."
Ms Swinson also told ITV News she would never enter into a coalition with Jeremy Corbyn nor Boris Johnson, under any circumstances.
Previously, she has told media that the Liberal Democrats must “own the failures” of the coalition.
Instead, she says she aims to grow the Liberal Democrats into one of the major parties.
“I think in politics at the moment, anything can happen,” she told ITV News.
“Under my leadership, what we’ll be offering is a different choice for people in our country so that we will be the largest party, if not the majority government.”
Scottish Liberal Democrat leader Willie Rennie had high praise for the new party leader, stating: “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.
“Jo is not tribal and will work with others to stop Brexit, stop independence and build a country that is richer, cleaner and greener.”