The Prime Minister was given the replica top by Belgian counterpart Charles Michel as the European Council meeting began.
Mrs May cracked a smile as she was handed the shirt with the number 10 on it.
Mr Michel had first shown the shirt, in its presentation box, to French President Emmanuel Macron before taking it out to give to Mrs May.
The number could have been a reference to Mrs May’s 10 Downing Street address, but it is also the shirt worn by Chelsea and Belgium star Eden Hazard.
Mr Michel also handed a Belgium football scarf to European Commission president Jean-Claude Juncker, who draped it over Ireland’s Leo Varadkar.
Mrs May will not be able to catch the game dubbed the “Brexit derby” because she will be locked in talks over a working dinner when the match kicks off at 8pm local time.
But a senior UK official said they could “make her aware” of the score “if needs be”.
Both England and Belgium have already secured their place in the knockout stages of the tournament.
Taoiseach Mr Varadkar said he would be supporting Belgium - nicknamed The Red Devils - in the game.
“I am here in Brussels in Belgium so of course I am going to be cheering for the home team,” he said.
“But of course if Belgium wins England will probably get an easier ride in the next round so perhaps it is one of those win-win scenarios.”