During the debate, Johnson ridiculed Corbyn's support for a new referendum while the Labour leader said the prime minister's pledge to "get Brexit done" actually meant seven years of trade talks.
Prime Minister Boris Johnson and opposition Labour leader Jeremy Corbyn went head-to-head over Brexit on Friday in the last televised debate before next week's election that will determine the path for Britain's departure from the European Union.
Six days before Britain votes in its second national election in less than three years, the debate is seen as the last chance for Corbyn to squeeze Johnson's lead in the polls, which mostly point to victory for the prime minister.
The two leaders set an ill-tempered tone to the debate by battling over how to leave the EU. Johnson ridiculed Corbyn's support for a new referendum in which Corbyn has said he would remain neutral, while the Labour leader said the prime minister's pledge to "get Brexit done" actually meant seven years of trade talks.
More than three years after Britain voted to leave the EU, the Dec 12 election will determine when, how and even whether Brexit happens.
"We have ample time to get on and build a new free trade partnership, not just with the EU but with countries around the world," Johnson said in the BBC TV debate.
But Corbyn countered that it would take the government seven years to negotiate a trade deal with the United States.
Polls show Johnson's governing party is well ahead of Labour. A Panelbase survey on Friday showed the Conservatives extending their lead slightly over the opposition party to nine points, up from eight a week ago.
Johnson, who renegotiated a new divorce deal with the EU in October, has promised to "get Brexit done," a slogan he has repeated constantly during campaigning to try to win over Labour supporters who backed leaving the bloc, and those who are simply fed up of the political haggling over the issue.
Britons voted by 52 percent in favour and 48 percent against in 2016 for Brexit but parliament has been stuck in deadlock over the way forward. If Johnson wins the majority he says he needs, Britain will leave the EU by Jan 31 and then seek to enact a trade agreement with the bloc by the end of 2020.
Corbyn: Johnson's promises are fraud
Earlier on Friday, Corbyn went on the attack, calling Johnson's promises a fraud and saying his Brexit deal would simply be the start of years of "painful negotiations and broken promises."
He also revealed a leaked government document which he said showed the divorce deal would lead to customs declarations and security checks between Britain and Northern Ireland, a direct contradiction to Johnson's statements that it would not create any barriers between the British province and the mainland.
The confidential Treasury report said the impact of the deal would be higher prices and that 98 percent of Northern Irish exporters would struggle to bear the additional costs.
"There will be other secret reports like this one in every government department that reveal the disastrous impact of Johnson's damaging deal," Corbyn said.
Johnson said the document was "complete nonsense."
He has mocked the stance adopted by Corbyn, who has said a Labour government would strike another exit deal with the EU to include a customs union, and then hold a second referendum on whether Britons wanted to accept it. Corbyn has said he will be neutral in that vote.
"Have we sent out search parties to discover Jeremy Corbyn's position on the EU?" Johnson said in a speech to supporters in southeast England. "If you want to get this thing done, if you want to the country to move forward, you've got to vote Conservative."