"The defendant was fully aware of the consequences of his actions," Doha's court of cassation ruled.
It said that Jabr, who was not in court, should face the death penalty, the original verdict handed down in 2014.
Use of capital punishment - by hanging or shooting - is rare in Qatar, with the last known case of the death penalty being carried out thought to date back to 2003.
Jabr had previously been convicted of the murder and sentenced to death, but that ruling was quashed, prompting Sunday's retrial.
In a lengthy verdict read out in court on Sunday, the judge dismissed all aspects of Jabr's defence. The defence argued at various times that he had acted in self-defence, was mentally incapable at the time of the murder, was interrogated by police without a lawyer and that the young teacher had committed suicide.
The judge, who said "several consequential strands of evidence" pointed to Jabr's guilt, recounted how the defendant and the teacher had met at a central Doha hotel.
They then went back to a property owned by Jabr, where they had sex, said the judge. It was afterwards that Jabr attacked Patterson, a teacher in Qatar from Kent in southeast England, stabbing her with a knife which had a 20-centimetre (almost eight-inch) blade, the court heard.