The left-winger stumbled after being confronted by an audience member called Callum during the Sky News and Channel 4 debate.
He admitted he met with various members of Irish republican party Sinn Fein, including current leader Gerry Adams, during the Troubles.
But he insisted he only did so to "bring about peace in Northern Ireland".
I wanted dialogue in Northern Ireland during the 1970s and 1980s
Mr Corbyn said: "I wanted dialogue in Northern Ireland during the 1970s and 1980s.
"I did make contact with Sinn Fein when their leadership was not allowed to travel to Britain, for example.
"I wanted there to be a peace process. We should all be pleased we've achieved a great deal through the Good Friday agreement."
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Jeremy Corbyn during a visit to Hackney Marshes Football Pitches, to highlight Labour's manifesto commitment to ensure 5% of the Premier League's television rights income is diverted to the grassroots game, during a General Election campaign
But the audience member went on to criticise Mr Corbyn for attending a commemoration for eight IRA members killed by the SAS in Loughgall.
The Labour leader said there was a period of silence for "everyone who died in Northern Ireland" at the 1987 event.
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When pressed further, Mr Corbyn said: "The contribution I made to that meeting was to call for a peace and dialogue process in Northern Ireland.
"It's only by dialogue and process we brought about peace in Northern Ireland and I think that's a good thing."
The Labour leader said he wanted to bring about peace in Northern Ireland
Mr Corbyn also rejected suggestions he would abolish the British monarchy and insisted he is a fan of the Queen.
Presenter Jeremy Paxman told the socialist, known for his republican beliefs, there is nothing in his party's manifesto about getting rid of the monarchy.
Mr Corbyn replied: "Look, there's nothing in there as we're not going to do it."