The court also ruled that the chairman of the upper house of parliament, the Senate, will replace Basescu for an interim period.
The interim president is Nicolae Vacaroiu, 63. He was prime minister during 1992-96 and now heads the Senate.
Lawmakers voted 322-108 on April 19 to suspend Basescu over allegations that he abused his position.
The court today rejected an appeal by Basescu. Its decision was largely formal, with judges only required by law to verify whether more than half the lawmakers voted to suspend the president.
Basescu today reversed his previous position, saying he will not resign despite his suspension.
According to the constitution, after the suspension, a referendum must be held within 30 days to decide whether to impeach the president.
However, more than half of Romanians registered to vote would have to cast ballots in favor of the impeachment, which would be virtually impossible given Basescu's high popularity.
(AP, Reuters, Mediafax, Realitatea TV)