The two leadership contenders will appear on a live ITV debate at 8pm in what is their only scheduled one-on-one encounter.
Mr Johnson hopes the appearance will cement him as the race’s clear frontrunner as polls reveal he is the current favourite among Conservative party members.
In turn, Mr Hunt will be hoping to turn around the contest with a strong performance.
The foreign secretary has been critical of his rival’s previous refusals to take part in televised debates, after Mr Johnson declined to take part in a live debate on Sky News.
An ally of Mr Hunt said at the time: “Bottler Boris and his complacent campaign have shown they can’t trust their candidate to turn up and perform.”
Both men have taken part in a number of hustings in front of party members, but Mr Johnson has only taken part in one previous TV debate when there were five contenders still left in the race.
Some have accused Mr Johnson of trying to avoid appearing in a debate before ballot papers were sent to party members.
The papers were sent last week to the party’s estimated 180,000 members and many will have already voted – meaning the debate may have little effect.
At a hustings on Monday, Mr Johnson warned that blocking a no-deal Brexit could play into the hands of Jeremy Corbyn and the Labour Party.
In a fresh warning to Tory MPs hoping to block a no deal, he said: “If we don’t get Brexit over the line then we face a haemorrhage of support.”
The Telegraph reported he said: “The risk they run is we will hand, by sheer incompetence, this government to a hard line Marxist.
“I make that point to Dominic Grieve and others who didn’t want to leave the EU. We’ve been very, very negative. We need to be much more robust and confident.”
Former attorney general Dominic Grieve has tabled an amendment to the Northern Ireland bill which would require the government to come back to the issue in October.
It is seen as an attempt to ensure the next prime minister cannot push through a no deal simply by suspending or “proroguing” Parliament.
Meanwhile Mr Hunt said he was confident he could negotiate a new deal with the EU – but was also prepared to “batten down the hatches” and prepare for no-deal on 31 October.
“I strongly believe if we approach this in the right way, there is a deal to be done,” he said, according to the Telegraph.
Author: Emily Mee and Alan McGuinness