The veteran politician confirmed he would take part during a rally this afternoon, in which he criticised the Tories for what he called "a stage-managed arms-length campaign".
He said: “I will be taking part in tonight’s debate because I believe we must give people the chance to hear and engage with the leaders of the main parties before they vote.
“I have never been afraid of a debate in my life. Labour’s campaign has been about taking our polices to people across the country and listening to the concerns of voters.
“The Tories have been conducting a stage-managed arms-length campaign and have treated the public with contempt. Refusing to join me in Cambridge tonight would be another sign of Theresa May’s weakness, not strength.”
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Jeremy Corbyn and Theresa May will not go head to head in a debate before June 8
Lib Dem leader Tim Farron, UKIP's Paul Nuttall, SNP deputy leader Angus Robertson, Green co-leader Caroline Lucas and Plaid Cymru leader Leanne Wood will also participate in the televised showdown.
But a Tory party spokesman confirmed there will be “no changes to the Prime Minister’s plans” regarding tonight’s debate.
Amber Rudd will still appear in place of Mrs May on the BBC show.
Mr Corbyn challenged Theresa May to "come and have a chat"
A Tory spokesman added: "There is a clear choice in this election: either the Brexit negotiations are led by Theresa May 11 days after polling day, or they will be put at risk by Jeremy Corbyn and his coalition of chaos."
While a source added: ”The public want to see a leader who can stare down the EU-27 at the negotiation table, not someone who will need their iPad to remember their dodgy facts in a debate."
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And following a speech this afternoon, Mrs May was asked why she will not attend the debate if she was "so strong, and Jeremy Corbyn is so weak".
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Laughing, she replied that Mr Corbyn seems keen to be on TV a lot but she was more worried about preparing for the Brexit talks.
She added that although she feels public scrutiny is important, she has done enough by taking questions from 'real voters' during the campaign and insisted that politicians squabbling amongst themselves does not do anything for voters.
Mishal Husain will moderate the debate, which is being filmed in Cambridge and will be shown on BBC One from 7.30pm this evening.
Each panellist will make an opening statement before taking questions from the audience.
Jeremy Corbyn had previously said he would not attend the debate if Theresa May also refused.
But today he changed his mind, saying: "Refusing to join me in Cambridge tonight would be another sign of Theresa May's weakness, not strength.”
Theresa May is sending Amber Rudd as her replacement
He also said the PM should "come and have a chat, come and have a debate" in his rallying speech today.
The show is the latest in a series of campaign broadcasts ahead dog the june 8 election.
Mrs May and Mr Corbyn took a grilling from Jeremy Paxman earlier this week, and both have already been interviewed by Andrew Neil in a series of programmes with party leaders.