The Buckingham Palace announced that Queen Elizabeth II has pulled out of the State Opening of Parliament and the reading of the Queen's speech this year because of "episodic mobility problems".
Instead, Prince Charles will deliver the speech on Tuesday on behalf of the 96-year-old monarch, the BBC quoted the Palace as saying late Monday night.
Also, Prince Charles and Prince William have jointly been given the authority to open Parliament in their capacities as "counsellors of state", allowing them to undertake such official duties if the monarch is temporarily unwell.
Until Monday evening, the Palace had been saying the Queen had hoped to attend.
But in a statement later, it confirmed that the Queen, in consultation with her doctors, had reluctantly decided not to attend the State Opening.
This is the first time since 1963 that the Queen will have missed this constitutional ceremony in Westminster.
She had only missed the speech twice during her 70-year reign, in 1959 and 1963, because of pregnancies, the BBC reported.
The State Opening of Parliament marks the start of the parliamentary year, with the Queen's speech setting out the agenda of the government and the laws that it wants to introduce.
In reaction to the development, a Downing Street spokesperson said: "The Prime Minister fully respects the wishes of Her Majesty and is grateful to the Prince of Wales for agreeing to deliver the speech on her behalf."