Ms Sturgeon, who last week debated against the leaders of the other six UK parties, went up against Scottish Labour’s Jim Murphy, Scottish Conservative leader Ruth Davidson and Willie Rennie of the Scottish Liberal Democrats.
She used the contest to repeat her call to Labour to work with the SNP - who could return a record number of MPs to Westminster on May 7 - to keep David Cameron and the Conservatives out of government.
She said: “If there is an anti-Tory majority in the House of Commons after the election, even if the Tories are the biggest party we will work with Labour to keep David Cameron out of Downing Street.”
It comes after leaked Whitehall memo claimed she would prefer Mr Cameron was prime minister - with the First Minister insisting this was “100% untrue”.
Mr Murphy pressed her who she wanted to see in Downing Street, asking the SNP leader: “Nicola, do you want Ed Miliband to be prime minister?”
She told him: “I don’t want David Cameron to be prime minister, I’m offering to help make Ed Miliband prime minister.”
Mr Murphy insisted: “Nicola, we don’t need your help. What we need is people north and south of the border, people in Scotland, people in England and people in across Wales coming together to kick out an out of touch government.”
The Scottish Labour leader added: “The only way to lock out the Tory party is to give the keys to the Labour Party. That’s the only way of preventing a Tory government.”
He said: “You can protest against the Tories with all sorts of parties, but there is only one guaranteed way of replacing them - that’s with Labour.
“This is a two for the price of one election: You can vote SNP and you get David Cameron thrown in for free, or you can vote Labour and you can throw David Cameron out for good.”
The Scottish Conservative leader also claimed the SNP and Ms Sturgeon were “desperate” to work with Mr Miliband and put Labour into government.
Ms Davidson said that was because the First Minister believed having the Labour leader as prime minister would be “good for independence”, adding: “Ed Miliband is weak, he’s not up to being prime minister and she’s going to be pulling the strings.”
Meanwhile Mr Rennie branded the exchanges as “immature” and said: “What we need to do is reflect what voters cast on May 7 and what we have sought to do in government is to bring stability to the country, return the country to recovery with the economy and do it fairly, that’s what our ambition has been.
“We will work with other parties in order to do that, to bring that stability, I just wish the other parties would adopt the same approach, I think that’s the mature approach to politics, the pragmatic approach to politics that people want in this country.”
SCOTSMAN TABLET AND MOBILE APPS