A three-judge panel at the supreme court in Jakarta unanimously rejected Lindsay Sandiford’s appeal against a death sentence.
The judges agreed with the decision taken by Bali’s Denpasar district court in January this year, which sentenced Sandiford to death.
The island’s high court had rejected her first appeal.
Sandiford, 56, from Cheltenham, Gloucestershire, was sentenced to death by firing squad after being found with cocaine worth an estimated £1.6m as she arrived on the Indonesian island on a flight from Bangkok, Thailand, in May last year.
A Foreign Office spokesman said: “We are aware that Lindsay Sandiford’s appeal to the Indonesian supreme court has been denied.
“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.
“We will continue to provide consular assistance to Lindsay Sandiford and her family at this difficult time.”
‘Drugs ring’ claim
Balinese police claim Sandiford was at the centre of a drugs-importing ring involving three other Britons.
She denies the allegations, claiming she was forced to transport the drugs to protect her children, whose safety was at stake.
Sandiford, originally from Redcar, Teesside, was arrested at Bali’s airport after 10.6lb (4.8kg) of cocaine was found in the lining of her suitcase during a routine customs check.
She was later accused of damaging the image of Bali and received the death sentence following her trial. The penalty was imposed despite prosecutors asking only for a 15-year jail term.
Under Indonesian law, Sandiford still has the opportunity to seek a judicial review of her case before appealing for a presidential pardon.