The Lib Dem leader explained his party had been revitalised by the Chesham and Amersham result, showing a way for the Tories to be beaten.
Speaking with The Scotsman ahead of his party’s conference, which starts on Friday, Sir Ed also claimed Mr Johnson was now simply unpopular on the doorstep.
He said: “Polls show it’s going to be a balanced Parliament and that empowers us even more, because in that situation our votes are even more important.
“So the chance of the Conservatives losing their majority is increased.
“They only lose their majority if Liberal Democrats beat Conservative MPs, and now we’ve shown we can and have a strategy for doing it.
“We think we can actually get Johnson out of government.
“That would have been more difficult to say about six months ago.
“He had a vaccine bounce and the fact we couldn’t go out and campaign because of Covid.
“The Conservatives can be beaten and the Liberal Democrats are core to that objective.”
The Liberal Democrats won Chesham and Amersham in June – a result Sir Ed claimed was part of a trend of the party fighting back.
Labour also took a surprise poll lead earlier this month after support for the Conservatives slumped to its lowest level since the general election on the back of Mr Johnson’s National Insurance tax rise.
A YouGov survey showed backing for the Tory Party falling five points to 33 per cent, while Labour’s share increased by one point to 35 per cent.
Sir Ed said: “We’ve got a spring in our step after the Chesham and Amersham result.
“I was saying at local elections when we started making progress in Wiltshire, Surrey, Oxfordshire and Cambridgeshire that we were knocking on the blue wall.
“Everyone said we couldn’t win it, but then we did and knocked down that blue wall.
“Thanks to a cheesy photo op people now realise that we can beat Conservatives.
“There has been this feeling that Johnson was invincible and now Liberal Democrats are beating the Conservatives.
“We're going to be winning quite a number of Tory seats.”
The Kingston and Surbiton MP repeatedly attacked the Prime Minister, claiming people were now telling him Mr Johnson was the reason they would not be voting Tory.
He said: “There was a real dissatisfaction with Boris Johnson on a personal level.
“He’s not a decent Prime Minister, they don’t think he represents their values. They think he’s incompetent and lazy, and at least two people said to me they would never for Conservative again as long as Boris Johnson is leader.”
“This narrative around that the Tory party are taking traditional conservative voters for granted.”
Sir Ed also praised the new leader of the Scottish Liberal Democrats Alex Cole-Hamilton, labelling him “exciting”.
He explained: “He’s brought new hope and that new hope comes not from [former leader] Willie Rennie not being brilliant.
“I think he would be the first to say that Alex brings a new face and new hope.
“I’m already enjoying working with Alex.
“My intention is to work at least as closely with Alex as I did with Willie Rennie.”