The commission "will now wait for the meaningful vote in the House of Commons", the spokesperson added.
As part of her bid to win support for the EU Withdrawal Agreement ahead of a looming crunch Commons vote, Mrs May will say that devolved administrations will have more powers after the United Kingdom quits the bloc.
After the rubber stamping, all eyes turn to British Prime Minister Theresa May to sell the deal to her recalcitrant parliamentarians over the next days and weeks - a huge task considering the intense opposition both her Conservative lawmakers and the political opposition have voiced toward the deal.
The 27 leaders took barely half an hour at a summit in Brussels to rubber-stamp a 600-page treaty setting the terms of Britain's withdrawal from the European Union on March 29 next year, and a 26-page declaration outlining a future free trading relationship.
Lithuanian president Dalia Grybauskaite said there could be a second referendum, general election or a re-opening of negotiations if the deal is voted down. And this time she wouldn't be losing Esther McVey and Dominic Raab, she'd be losing her most senior ministers.
The PM received a largely hostile reception as she told the House of Commons her Brexit deal "delivers for the British people", and warned that rejecting it would put the United Kingdom on the path to division and uncertainty.
At a bittersweet meeting, European Union leaders expressed sadness at the departure of Britain, the first country ever to leave the bloc.
But this hard chapter was always going to be the easy part. "There doesn't seem to be a clear majority in Parliament for any alternative to the deal: not for "no deal" and leaving just with the WTO rules; not for a referendum again; not for 'Remain'".
But European Council President Donald Tusk, who broke the news of the agreement on Twitter, said he would not speculate on what would happen in such a situation, saying: "I am not a fortune teller". Alternatively, May could face a leadership challenge from within her own party.
"Absolutely she can", he told BBC1's The Andrew Marr Show.
May defends draft Brexit deal
Should May's bill be defeated, she will nearly certainly have to resign as prime minister.
The British Parliament rejects the deal?
Lawmakers will vote: A vote is expected before Christmas. May's critics say it leaves Britain tied to European Union regulations that it will no longer have a say in setting. So far at least, the government's proposed Brexit deal has not gained widespread political support and it is not clear that it will be implemented. Leaders generally dislike the departure but now want to pin down the deal to free them to focus on other, more pressing problems such as populism, struggling economies and Russian Federation.
The report's authors, Arno Hantzsche, Amit Kara, and Garry Young, said "the main focus of our analysis is on how the government's proposed Brexit deal is likely to affect the economy, leaving aside the effect it might have on uncertainty".
"This is that deal. A deal that delivers for the British people".
Brexiteers want negotiators to return to Brussels to amend the deal, but European leaders have said that they have little room to improve it and that there is nothing more to talk about.
Irish Prime Minister Leo Varadkar said he thought May's chances of getting the agreement through Parliament were strong.
May will now embark on an intensive nationwide campaign to promote the deal with voters across the country and lawmakers in London.
Mr Smith sought to spread some Christmas cheer to Conservatives feeling frosty towards Mrs May's deal in the letter, wishing MPs and their families "a very happy Christmas" and thanking them for their support this year.