It is the 56th time Her Majesty has opened a new parliamentary session during her reign, but the first time she has done it for a coalition government.
The pomp and ceremony began, as tradition dictates, with the monarch journeying in the Irish State Coach from Buckingham Palace to the Palace of Westminster, accompanied by the Duke of Edinburgh.
Ahead of her, escorted by members of the royal household, travelled The Regalia – the Imperial State Crown, the Cap of Maintenance and Sword of State – in their own carriage.
Meanwhile, Prime Minister David Cameron and Deputy Prime Minister Nick Clegg walked on foot from Downing Street to join other MPs in the Commons.
On arrival, the Queen donned the Imperial State Crown and parliamentary robe and led the customary procession to the House of Lords, where assembled guests included Baroness Thatcher and Britain's new 'First Lady' Samantha Cameron.
After she took to the throne, the deputy Gentleman Usher of the Black Rod, Ted Lloyd-Juke, summoned members of the House of Commons.
The incumbent Black Rod, Lieutenant General Sir Freddie Viggers, was unable to take part in Tuesday's ceremony, after being rushed to hospital last week having suffered a reported multiple stroke.
With Mr Cameron, Mr Clegg and other MPs gathered in the Lords, the Queen delivered her Speech outlining the new government's plans for the next year and a half.
Among the coalition's programme of 22 new bills she read out were plans to tackle the budget deficit, scrap ID cards and reform schools, the police and the political system.
Although read by the Queen, the speech is drawn up by the Government and approved by the Cabinet.
The pageantry ended with the Queen and Prince Philip returning to Buckingham Palace in the royal carriage, to the accompaniment of the Coldstream Guards playing the national anthem.
The Queen has opened every Parliament but two during her 56-year reign.
Those were in 1959 and 1963, when she was pregnant with Prince Andrew and Prince Edward.