The Brexit Party has "killed the Liberal Democrats and hurt the Labour Party", Nigel Farage has claimed.
The Conservatives won 365 seats in the 2019 general election - up 47 from before the vote.
Labour won 203 seats (down 59), the SNP 48 (up 13) and the Lib Dems 11 (down by one). The Brexit Party did not win any.
But Mr Farage said the party took thousands of votes from Tory opponents and he was happy with its "influence".
Speaking to the BBC after the announcement of the exit poll results, he said the Conservatives would win or come close in dozens of seats where they otherwise would not have done without the Brexit Party's help.
He added: "I killed the Liberal Democrats and I hurt the Labour Party."
He said the party had killed off hopes of another referendum.
Meanwhile, Brexit Party chairman Richard Tice failed in his bid to win the constituency of Hartlepool.
MEP Mr Tice received 10,603 votes - around a thousand fewer than the Conservative candidate and nearly 5,000 fewer than Labour's Mike Hill, who won the seat.
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The election delivered a Commons majority of 80 for Prime Minister Boris Johnson.
Mr Farage claimed that Tory majority would not exist if his party had not withdrawn from fielding candidates in 317 Conservative-held seats.
"I can tell you that if we had stood in every seat in the country it would have been a hung Parliament," he said. "That would have been a disaster."
He added: "I was determined, in this election, we would use our influence to stop a second referendum. That overwhelmingly was behind our decision to stand down in 317 seats.
"Jo Swinson herself said that effectively poleaxed her campaign. And then taking the fight to Labour was important.
He added: "Would I like to have won a few seats? Yes of course."
Born out of frustration with delays to the UK's departure from the EU, the Brexit Party was launched in April 2019, with ex-UKIP leader Mr Farage leading it.
When asked if the Brexit Party was now "finished", Mr Farage said: "We've used our influence, that's the important thing. If we get Brexit... we've done a good job."
Arron Banks, who campaigned to leave the European Union alongside Mr Farage, said the exit poll suggested a "brilliant victory" for Boris Johnson, who now had a "strong majority" to negotiate a free trade deal with the EU.
He added that while the Brexit Party was now "over", the "pressure" applied to the Tories had helped return them to their "roots".
"We set out to make the Conservative Party conservative again - and it's job done," he said.