LONDON — After more than three years of anguished national debate, multiple cliff-hanging votes, and two general elections, Britain’s Parliament voted by a wide margin on Friday to advance Prime Minister Boris Johnson’s Brexit plan, paving the way for the country to leave the European Union next month.

For all the drama of the moment, the vote, 358 to 234, was a foregone conclusion. After the landslide victory of Mr. Johnson and his Conservative Party last week, the outcome was never in doubt — proof, as politicians like to say, that elections have consequences.

With Parliament now firmly under the grip of the Conservatives, the days of fierce debate over Britain’s future, which had thwarted Mr. Johnson and his predecessor, Theresa May, are gone. The House of Commons, so recently a grand arena for democratic defiance, has become an efficient vehicle to enact Brexit.

The House of Lords must still give its imprimatur, but it is unlikely to obstruct a bill that was enshrined in the manifesto of the Conservative Party and formed the centerpiece of Mr. Johnson’s winning campaign.