Cornwall B&B owners Hazelmary and Peter Bull refused to let civil partners Steven Preddy and Martyn Hall stay in a double room at their facility in Cornwall in 2008. They offered them two single rooms but not a double.
As Christians. They regard any sex outside marriage as a “sin”.
They denied discriminating against Mr Hall and Mr Preddy, from Bristol.
They said their decision was founded on a “religiously-informed judgment of conscience”.
The Supreme Court ruled against them at a hearing in London.
In 2011 a judge at Bristol County Court concluded that the Bulls had acted unlawfully and ordered them to pay a total of £3,600 damages to the gay couple.
The following year the Court of Appeal dismissed an appeal by the Bulls following a hearing in London. The couple had asked the Supreme Court to overrule the Court of Appeal but the Supreme court refused.
Mrs Bull said: “We are deeply disappointed and saddened by the outcome.’