Boris Johnson has said the UK will "open a new chapter" thanks to the country's post-Brexit EU trade deal - which the government hopes to ratify in parliament in a single day.
The prime minister hailed the "astonishing speed" with which the deal was agreed and said it "demonstrates how Britain can be at once European and sovereign".
MPs and peers are debating the deal ahead of a vote which could see the EU (Future Relationship) Bill passed by the end of the day.
If approved, the trade deal, which was agreed between the UK and EU on Christmas Eve, will come into force on 1 January following the end of the Brexit transition period on 31 December.
The prime minister told the House of Commons: "We are going to open a new chapter in our national story, striking free trade deals around the world and reasserting global Britain as a liberal outward-looking force for good.
"Now with this Bill, we're going to become a friendly neighbour, the best friend and ally the EU could have."
He added: "It took nearly eight years for the Uruguay round of world trade talks to produce a deal, and five years for the EU to reach a trade agreement with Canada, and six for Japan.
"We have done this in less than a year, in the teeth of a pandemic, and we have pressed ahead with this task, resisting all calls for delay, precisely because creating certainty about our future provides the best chance of beating COVID and bouncing back even more strongly next year."
MPs were recalled to the Commons from their Christmas break to scrutinise the 1,246-page agreement in a single day.
Mr Johnson is expected to see the deal pass through with few problems after Labour said they would vote in favour of the agreement.
Labour leader Sir Keir Starmer said the agreement was flawed, but the alternative of ending the transition period without a deal would be even worse.
He told MPs: "This is a thin deal. It has got many flaws but a thin deal is better than no deal.
"Not implementing this deal would mean immediate tariffs and quotas with the EU which will push up prices and drive businesses to the wall.
"It will leave huge gaps in security, a free-for-all on workers and protections and less stability for the Northern Ireland protocol."
He grilled the PM on his claim that there will be "no non-tariff barriers to trade" under the terms of the deal.
"The prime minister knows it's not true, every member of this House knows it's not true," added Sir Keir as he challenged the PM to respond.
Mr Johnson duly did so, telling MPs: "This is a zero tariff, zero quota deal."
A group of influential Conservative Brexiteers - the European Research Group - declared its support for the deal and said it "preserves the UK's sovereignty as a matter of law".
However, fishing industry leaders have said they feel "angry and betrayed" by the agreement, claiming many businesses would be worse off.
If the EU (Future Relationship) Bill is passed in the Commons and the Lords, its provisions will come into force at 11pm on 31 December when the current Brexit transition period expires.
MPs will vote on the agreement at about 2.30pm. Peers are expected to debate the deal in the Lords long into the evening after they begin at 3pm.
Earlier in the day, European Commission president Ursula von der Leyen and European Council president Charles Michel formally signed the agreement.
Mr Michel said the deal was "fair and balanced" and "fully protects the fundamental interests of the European Union".
Following the brief ceremony in Brussels, the documents were being flown to London by the RAF for Mr Johnson to sign in Downing Street.