10 Downing Street will fly the flag of St George for England's matches in the World Cup.
David Cameron has ordered the flag to be raised as a mark of support for Roy Hodgson's team in Brazil.
The announcement comes just days after Mr Cameron wished the England team "the best of British" at Prime Minister's Questions in the House of Commons.
It will go up tomorrow afternoon after the trooping of the colour ceremony, ahead of England's tie with Italy in the evening, and will be flying for the later matches against Uruguay and Costa Rica, as well as any subsequent games if the team progresses to later rounds.
Recent Home Office analysis claimed there was a "high probability" that England would not progress beyond the group stage.
The flag of St George was also flown during the World Cup finals of 2006 and 2010.