Watch the debate and vote on the Internal Market Bill
MPs voted in favour of a second reading of the Internal Markets Bill by a majority of 77.
The controversial Bill, which attracted criticism from former prime ministers and rebel Conservative MPs, includes legislation that will override aspects of the Withdrawal Agreement which was signed by both the EU and UK in October.
But in the House of Commons on Monday, MPs approved it, giving it a second reading by 340 votes to 263.
MPs will begin detailed line-by-line scrutiny of the Bill on Tuesday, with votes expected next week on amendments to the Northern Ireland provisions which some Tories may back.
The Bill aims to end the legal legitimacy of the Northern Ireland protocol - contained within the Withdrawal Agreement - in areas such as customs and state aid and financial assistance.
It will ensure goods from Northern Ireland continue to have unfettered access to the UK market while making clear EU state aid (a subsidy or any other aid provided by a government that distorts competitions) rules - which will continue to apply in NI - will not apply in the rest of the UK.
The PM said it is "necessary" to row back on aspects of a Brexit agreement - and in the process breach international law - in order to "stop a foreign power from breaking up our country".
Ahead of the vote, Mr Johnson urged MPs to back the Bill saying it was a "safety net" that would “guarantee the economic and political integrity of the United Kingdom”.
He said the legislation was necessary to prevent the EU taking an “extreme and unreasonable” interpretation of the provisions in the Withdrawal Agreement relating to Northern Ireland.
He said some in Brussels were now threatening to block UK agri-food exports to the EU and to insist on tariffs on all goods moving to Northern Ireland from the rest of the UK.
However some senior Conservatives warned they could not support the legislation in its present form after Northern Ireland Secretary Brandon Lewis admitted it would breach international law in a “very specific and limited way”.
Among the Tories who rebelling against their party were former Chancellor Sajid Javid, former attorney general Jeremy Wright and veteran Conservative backbencher Sir Roger Gale.
“I believe very strongly we should obey international law. I believe the United Kingdom’s word is its bond and I think this is damaging our international reputation for honesty and straight-dealing,” Sir Roger said.
Sir Roger acknowledged he was in a “tiny minority” among Tory MPs but predicted others could rebel when the Commons comes to consider amendments to the Bill next week.
Commons Justice Committee chairman, Sir Bob Neill, has tabled an amendment requiring a vote of Parliament before ministers can exercise the new powers in the Bill, and urged MPs to “take the opportunity to change and improve these clauses”.
Sir Roger said: “I took a view that you fight this tooth and nail at every step. Others have quite clearly decided they want to hold their fire for Bob Neill’s amendment. There is much to play for yet."
Summing up the reading before MPs went to vote, Cabinet Office Minister Michael Gove said that the UK is committed to making a success of its negotiations with the EU.
“What this Bill is not doing is not walking away from negotiation with the European Union. Those negotiations go on,” Mr Gove told the Commons.
“We’re committed to making a success of those negotiations. What this Bill is not about is abandoning the Withdrawal Agreement, the Withdrawal Agreement is there, we are safeguarding the rights of three million EU citizens in the UK, just as EU nations are safeguarding the rights of one million UK citizens in the EU.
“And this Bill is certainly not about declining to implement the Northern Ireland Protocol.”
For Labour, shadow business secretary Ed Miliband – standing in for Sir Keir Starmer who is in coronavirus self-isolation – said Mr Johnson had only himself to blame for signing up to the Withdrawal Agreement.
“Either he wasn’t straight with the country about the deal in the first place or he didn’t understand it,” Mr Miliband said.
“Because a competent government would never have entered into a binding agreement with provisions it could not live with.”
Labour’s amendment to block the United Kingdom Internal Market Bill from receiving a second reading was defeated earlier by 349 votes to 213, majority 136.
The government welcomed the Commons vote to give the UK Internal Market Bill a second reading, saying that it was now critical that the legislation completed its passage through Parliament by the end of the year.
“We welcome the fact that this vital Bill has passed its second reading,” a spokesman for the Government said.
“It will protect the territorial integrity of the UK and the peace in Northern Ireland, safeguarding trade and jobs across all four corners of the UK following the end of the transition period.
“It is critical that we pass this Bill before the end of the year.”