Johnson struck an exit agreement with the EU on Thursday, just ahead of a summit of European leaders in Brussels.
He then aimed to put the agreement to a vote at an extraordinary session of the British parliament on Saturday.
But, in a major blow to the head of government, British lawmakers on Saturday voted 322-306 to postpone a decision on whether to back his Brexit deal.
The measure adopted by British MPs aims to ensure that their country will not crash out of the EU without a divorce deal on the scheduled October 31 departure date.
The BBC quoted Johnson as saying that he would press on "undaunted" with his Brexit strategy despite losing a vital vote in the House of Commons.
He vowed to introduce legislation needed to implement his agreement in Parliament next week, the British broadcaster reported.
But Johnson will be compelled to ask the EU for an extension beyond October 31 after MPs backed a motion designed to rule out a no-deal exit, the BBC reported.
The impact of Britain’s shock 2016 decision to withdraw from the bloc has been closely watched in Warsaw as there are around a million Poles living in the UK, constituting that country’s largest minority community.
Polish Prime Minister Mateusz Morawiecki said on Thursday that the Brexit deal struck by Johnson with Brussels would secure the rights of Poles living in Britain.
Morawiecki said earlier this year that a no-deal Brexit would be “a bad solution” for both Britain and the European Union.
In his first speech as prime minister, Britain's Johnson in July promised EU nationals in his country "absolute certainty" that they can “live and remain” in the UK after Brexit.
He also said at the time that “Brexit was a fundamental decision by the British people” and that this decision must now be respected.
Britain’s previous Prime Minister Theresa May in December told Poles living in her country that they were welcome and would be able to stay in the UK after Brexit.
(gs)
Source: BBC, CNN