The petition on Parliament's website reached the figure on the same day that it was set up, having already amassed the 100,000 figure required for it to be debated in Parliament.
The petition, which was created by Mark Johnston on Parliament's website, states that Parliament should not be prorogued unless there is another extension of the Brexit deadline or the idea of leaving the European Union is scrapped altogether.
It says: "Parliament must not be prorogued or dissolved unless and until the Article 50 period has been sufficiently extended or the UK's intention to withdraw from the EU has been cancelled.”
The odds of an early General Election have been slashed by bookies following Mr Johnson’s announcement, while a legal bid has been launched to prevent the PM from suspending Parliament.
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Campaigners against Brexit branded the PM's plans an "assault on democracy" as they revealed a motion has been submitted to the Court of Session in Edinburgh - the highest civil court in Scotland - asking for the move to be suspended.
The case is being taken by a cross-party group of more than 70 MPs and peers, with the support of the Good Law Project.
Its director Jolyon Maugham QC confirmed a motion had been filed.
One of the politicians involved, Labour Edinburgh South MP Ian Murray, said: "Boris Johnson's plan to suspend Parliament is an assault on our democracy.
"This is the people's Parliament and the people deserve to have their representatives in Parliament during this vital period.
"Legal action to prevent the Prime Minister suspending Parliament has already been fast-tracked through the courts and we are now seeking an emergency hearing to prevent this undemocratic action.
"A no-deal Brexit would be catastrophic for Scotland and the UK, and we will do everything we can to stop Boris Johnson inflicting such hardship on the people.
"The final say on Brexit should be handed back to the people.”
The group had already filed a petition at the Court of Session as part of an effort to stop Mr Johnson from being able to prorogue Parliament, with a judge ordering there should be a fast-track hearing in the case.
A hearing has been scheduled for Friday September 6, but SNP MP Joanna Cherry, who is also involved in the case, said they are now looking to see if that could take place sooner.