Johnson is scheduled to meet the Queen at Buckingham Palace where he will be invited to form a new government.
He is also expected to announce senior cabinet posts, including chancellor of the exchequer and home secretary.
Johnson won a decisive victory over Foreign Secretary Jeremy Hunt for the party’s leadership.
After his victory, Johnson said his priorities were to deliver Brexit, unite the country and defeat Labour leader Jeremy Corbyn.
Johnson will inherit a wafer-thin parliamentary majority and like his predecessor Theresa May, he will continue to rely on the support of the Democratic Unionists of Northern Ireland to govern.