If he loses, he'll stand down as prime minister.
It's after a steady stream of Conservative MPs called for him to quit over illegal lockdown parties at Downing Street.
Number 10 says Mr Johnson 'welcomes the opportunity to make his case to MPs'.
Graham Brady, who heads the committee which will oversee the ballot, confirmed at least 54 Tory politicians have asked for it. "I notified the prime minister yesterday that the threshold had been reached. We agreed the timetable for a confidence vote to take place and he shared my view that that vote should happen when it could reasonably take place. And that would be today."
