Johnson and his rival, Foreign Secretary Jeremy Hunt, spent the last month crisscrossing the country seeking to win over the less than 200,000 Conservative Party members who chose Britain’s new leader.
Johnson garnered 92,153 votes and Hunt 46,656, according to BBC. Voting closed on Monday and the result was announced on Tuesday morning.
Johnson will formally take over as prime minister on Wednesday afternoon, succeeding Theresa May who stepped down over her failure to get parliament to ratify her Brexit deal. May pledged “full support” to Johnson in a congratulatory tweet.
The victory is a triumph for the 55-year-old Johnson, an ambitious but erratic politician whose political career has veered between periods in high office and spells on the sidelines.
Finance Minister Philip Hammond and two other cabinet ministers have already announced they will step down, as has junior foreign minister Alan Duncan.
Johnson, a former London mayor who resigned as foreign minister a year ago over May’s Brexit plans, was the clear favorite to replace May, with several polls putting him on around 70 percent.
He inherits a political crisis over Britain’s exit from the European Union, currently due to take place on October 31. Johnson must persuade the EU to revive talks on a withdrawal deal that it has been adamant cannot be reopened, or else lead Britain into the economic uncertainty of an unmanaged departure.
The only deal on the table has been rejected three times by parliament and many lawmakers — including pro-EU rebels in the Conservative Party — are also vowing to block Johnson trying to take Britain out of the EU without a deal.
He has said he would ramp up preparations for a no-deal to try to force the EU’s negotiators to make changes to the accord.
“We will of course be pushing our plan into action, and getting ready to come out on October 31st, come what may […] do or die, come what may,” Johnson told TalkRadio last month.
Johnson is not likely to start announcing key ministerial appointments until Wednesday.
Brexit without a divorce deal — as anti-EU hardliners would like — would abruptly wrench the world’s fifth largest economy away from the bloc. Critics say this would undermine global growth, buffet financial markets and weaken London’s position as the pre-eminent international financial center.