The UK Supreme Court has ruled Boris Johnson's decision to suspend Parliament until 14 October was "unlawful".
The Supreme Court also said the UK Parliament can meet "as soon as possible."
Britain’s most senior judge, Lady Hale, sitting with 10 other Supreme Court judges, ruled unanimously that the advice he gave to the Queen was unlawful.
Lady Hale, said: “Parliament, as elected representatives of the people, has a right to a voice... the effect on our elected democracy was extreme”.
House of Commons Speaker John Bercow has instructed that the UK parliament shouldl return to work on 25 September.
"In the light of that explicit judgment I have instructed the house authorities to prepare ... for the resumption of the business of the House of Commons. Specifically, I have instructed the house authorities to undertake such steps that are necessary to ensure that the House of Commons sits tomorrow ... at 11.30 am" Bercow said.
The Labour Party leader, Jeremy Corbyn, said the ruling showed the Prime Minister had acted wrongly and he told delegates at the party's conference in Brighton that Mr Johnson should "consider his position".
The leader of the Brexit Party, Nigel Farage, said prorogation was the worst political decision which had ever been made and he called on Mr Johnson to fire his adviser, Dominic Cummings.
Dominic Grieve, one of the 21 rebel Tory MPs who defied the Prime Minister, told the BBC the Prime Minister's position was now in question in light of his unlawful advice to The Queen.
A Downing Street spokesman told the BBC it was "currently processing the verdict."
Opponents of the Prime Minister, including prominent Remainer Gina Miller, had argued he had overstepped the mark legally when he prorogued Parliament.