Two prominent EU officials signed the trade deal with the United Kingdom on Wednesday.
President Ursula von der Leyen of the European Commission and EU President Charles Michel did so during a short ceremony.
The agreement was grasped after months of negotiations. The text is now being flown to London by the British Air Force.
Prime Minister Boris Johnson will also sign there. The parliaments of the United Kingdom and the EU also have to give their approval.
Parliamentarians in the British House of Commons have already started their debate on the deal. They will likely approve it sometime in the afternoon.
The vote is expected around 2.30 p.m. UK time. After that, the unelected Upper House, the House of Lords, must also give the green light.
Final approval by the British Parliament is expected during the day. The deliberation in the House of Lords can last until midnight, according to British media.