The impeachment debate in the lower house of parliament is due to start later on Friday and continue until Sunday’s vote. If two-thirds of MPs vote for impeachment, the motion will pass to the Senate, BBC reported.
Rousseff, who said her opponents are plotting a “coup”, faces claims she manipulated government accounts.
She has vowed to fight to “the last minute” despite the desertion of three allied parties ahead of Sunday’s vote in the lower house of parliament.
The Supreme Court made its decision in an extraordinary session on Thursday night.
The injunction to suspend the vote was filed by Attorney General Jose Eduardo Cardozo who claimed that alleged procedural failings had violated the president’s right to a defence.
Seven of 10 justices voted to reject the motion even before the Supreme Court session had finished.
Judges first looked at a request made by the ruling Communist Party of Brazil (PCdoB), which asked that they change the way in which 513 deputies will be called to vote next Sunday to decide whether the case will be sent to the Senate, EFE reported.
The PCdoB had questioned the decision that deputies will be called to vote in blocks determined by the states they represent, but the Supreme Court said the model fits the Constitution and the internal rules of the legislature.
On the table, there are four lawsuits dealing with technicalities but the petition filed by the Attorney General could interrupt the entire process.