Ms Swinson has insisted the Lib Dems would not put either Mr Corbyn or Boris Johnson into Downing Street in the event of no party securing a Commons majority in the December 12 General Election.
She made the claim on a day she promised £50 billion to go towards infrastructure outside London.
Asked about how she would react if Mr Corbyn quit as Labour leader after the poll result, Ms Swinson said: “Obviously we don’t know who the personalities would be in that circumstance, but we will obviously take a view on that depending on what circumstance we find ourselves in.
“I have been working with people from the Labour Party, and people from the Conservative Party, and the SNP, and Plaid Cymru, and the Green Party to try and stop Brexit and try and secure a people’s vote so that we can remain in the EU.
“I’ve been doing that for the last couple of years and I will certainly be continuing to do that.
“Obviously, Jeremy Corbyn… is completely unfit to be prime minister, as is Boris Johnson for a whole host of different reasons.
“And so, if Labour are in a situation where they consider that Jeremy Corbyn is no longer fit to lead them, then we will of course look to keep working with people to try and secure a people’s vote.”
The party has also pledged a £50 billion fund for infrastructure investment outside London if they win power.
The Regional Rebalancing Programme would help tackle ingrained inequality across the UK, the party said.
The Lib Dems say the money would be ring-fenced and spent on sustainable infrastructure projects, such as electrifying railways, increasing the availability of charging points for electric vehicles and improving broadband access.
Meanwhile, when asked what the “naughtiest” thing she had done was, Ms Swinson said: “I did smoke a fair bit of cannabis at university.
“I don’t know whether that counts as particularly naughty, but your readers and viewers will be able to make up their own mind on that.”
Pressed to define a “fair bit” of cannabis, Ms Swinson said: “It wasn’t just one, and I did inhale.”