The SNP’s Westminster leader said he was “pretty confident” that not only the debate will happen, but Scotland will vote to become independent.
He made the comments during an on-stage interview with the journalist Graham Spiers at the Edinburgh Fringe on Thursday.
Elsewhere, Mr Blackford revealed he listens to “things like Meat Loaf” to help get him in the right frame of mind before Prime Minister’s Questions.
First Minister Nicola Sturgeon wants to hold a second referendum next year, but the UK Government has refused to agree to this.
A Supreme Court battle is set to take place in October to determine whether Holyrood has the power to legislate for another vote on its own.
Speaking at The Stand's New Town Theatre, Mr Blackford said both the SNP and the Greens stood on a manifesto promise of having a referendum on independence.
He said: “There’s an independence majority, and Westminster should recognise that it’s the right of those who live in Scotland to have that debate.
"It’s not a good look for any Prime Minister in Westminster to keep saying ‘no, you can’t’.
"That is a denial of democracy, so, of course, on the basis of that we’re having to go to the Supreme Court, let’s see what happens.
"I hope that there is an opinion in our favour, and then we can get on and have that debate.”
The MP for Ross, Skye and Lochaber added: "The debate we want to have is what is the future for Scotland. It goes back to the point I made earlier, of having that debate with other parties.
"But one way or the other, that referendum will happen.
"And I have to say, I’m pretty confident not only will that debate happen, but Scotland will vote to become an independent country."
Elsewhere, Mr Blackford said he was concerned about the atmosphere in politics and admitted he would struggle to recommend the career to young people.
He said: "I’m not sure that if I was to advise a young person today I would encourage them to do that.”
He said a lot of people get “quite dreadful abuse” on social media, and there is a “collective responsibility” to improve debate.
Mr Blackford insisted political opponents can be friends, revealing he previously developed “quite a strong friendship" with Lord Richard Harrington, the Conservative refugees minister.
He agreed with an audience member who questioned whether PMQs had become “slightly redundant” as the Prime Minister doesn’t actually answer questions.