Commons speaker Sir Lindsay Hoyle told MPs shortly before 12.30am on Thursday that the Queen had formally rubber stamped the European Union (Future Relationship) Act 2020.
Her approval marked the final step of a 14-hour process, which saw the bill pass both the House of Commons and the House of Lords in just a single day, with the draft legislation – which was more than 1,200 pages long – published just days before, on Boxing Day.
The trade deal comes after years of negotiations between the UK and the EU, following the UK’s vote to leave the bloc in June 2016.
After prolonged fears of a no-deal Brexit, a deal was finally struck and announced on December 24, meaning that when the transition period comes to an end at 11pm the UK will start trading with the EU on the terms set out in the deal.
Speaking just after the bill was given royal assent, Boris Johnson said the UK’s destiny “now resides firmly in our hands”.
He said: “We take on this duty with a sense of purpose and with the interests of the British public at the heart of everything we do.
“11pm on December 31 marks a new beginning in our country’s history and a new relationship with the EU as their biggest ally. This moment is finally upon us and now is the time to seize it.”
MPs backed the bill by 521 to 73 at its third reading, while peers gave it an unopposed third reading late on Wednesday night.
Labour supported the deal, despite misgivings from some pro-European MPs who said they would be abstaining or voting against.
Earlier in the day, European Commission president Ursula von der Leyen and European Council president Charles Michel formally signed the agreement.
Following the brief ceremony in Brussels, the documents were then flown to London by the RAF where the PM put his name to it.