The pound slid on the surprise news, which opponents branded a “coup” and a “declaration of war”, although US President Donald Trump weighed into the row by praising Johnson as “great”.
The Conservative leader’s move to close parliament for a month will give pro-EU lawmakers less time than they expected to try to thwart his plans for a possible no-deal Brexit on October 31.
Queen Elizabeth II has approved the request to close what has been the longest session of parliament in nearly 400 years, and reopen it on October 14 setting out Johnson’s fresh legislative programme.
Seemingly caught on the hop, incensed anti-Brexit MPs were left scrambling for a way to stop the move.
Johnson’s announcement came after six opposition parties said on Tuesday they would first seek to legislate to prevent leaving the EU without a deal when parliament returns from a summer recess next week.
Jeremy Corbyn, the leader of the main opposition Labour Party, has said he wants to call a vote of no-confidence in Johnson’s government, which commands a majority of just one seat.
John Bercow, the speaker of parliament’s lower House of Commons, described the closure as a “constitutional outrage” designed to stymie debate on Brexit, with Britain currently on course to crash out without a divorce deal.