The court annulled the first round of voting, which was held on September 7 and won by former leader Mohamed Nasheed, and ordered a fresh ballot within the next 13 days.
"The court in a majority decision of 4-3 annulled the elections and ordered fresh elections by October 20," a court official told reporters after the long-awaited judgement.
The presidential vote was seen as a key test for the country a year and a half after the violent ousting of Nasheed, the Maldives' first democratically elected president, who came to power in 2008.
The court ordered that if no candidate secured an absolute majority in the fresh elections a run-off election should be held before November 4.
buy lipitor online buy lipitor online no prescription
A new president must be in office by November 11, a deadline set by the 1978 constitution that ended 30-year one-party rule by former autocrat Maumoon Abdul Gayoom.
Local and international observer groups had found the first round of voting to be free and fair.
But the Supreme Court suspended a run-off ele