Pubs will be able to stay open an extra two hours on both days until 01:00.
The Queen celebrates two birthdays each year – her actual birthday on 21 April and her official birthday on a Saturday in June – this year on 11 June.
The longer opening hours also coincide with England’s and Wales’s first games in the European football championships. On Saturday 11 June, Wales play Slovakia at 17:00 BST and England play Russia at 20:00 BST.
There will be a series of events over the June weekend to mark the Queen’s 90th birthday. These will include a street party in The Mall, a service of thanksgiving at St Paul’s Cathedral and the traditional Trooping the Colour ceremony, also known as the Queen’s Birthday Parade, at Horse Guards Parade.
Announcing the extension during Prime Minister’s Questions, Mr Cameron said, “I’m sure that will be welcomed right across the House.”
Late opening hours have taken place on other occasions in recent years including the wedding of the Duke and Duchess of Cambridge in 2011, the Queen’s Diamond Jubilee in 2012 and the 2014 World Cup.
Pubs wishing to extend their opening hours for a one-off occasion normally need to apply to their local council for a temporary event notice. Scotland and Northern Ireland have separate licensing regulations.