The three-member judge panel yesterday unanimously rejected Lindsay Sandiford's appeal, said Supreme Court spokesman Ridwan Mansur.
Sandiford, 57, was arrested last year when 3.8 kilograms of cocaine was discovered stuffed inside the lining of her luggage at Bali's airport. During the trial, she said she was forced to carry the drugs by a gang that threatened to hurt her children.
She was found guilty in January by a district court and sentenced to face a firing squad. She lost an appeal three months later after the Bali High Court upheld the lower court's ruling.
"We are aware that Lindsay Sandiford's appeal to the Indonesian Supreme Court has been denied," Adam Rutland, spokesman for the British Embassy in Jakarta, said in an email. "In line with our strong opposition to the death penalty in all circumstances, we will consider how to support any application for judicial review or clemency that Lindsay Sandiford chooses to make."
Indonesia has strict anti-drug laws and most of the more than 40 foreigners on its death row were convicted of drug charges.