Hassan al-Mandlawi, 32, and Al-Amin Sultan, 30, both Swedish nationals, were convicted after graphic videos showed them taking part in the killing of two men in the northern Syrian city of Aleppo.
The footage, discovered on a USB stick in Sultan's home, shows two men speaking in Swedish and giving directions before one prisoner is beheaded and another has his throat slashed with a knife.
Both are heard cheering while one severed head is held up.
But the court convicted Mandlawi and Sultan of "terror crimes" after the National Forensic Centre confirmed they were the men seen in the film.
Prosecutor Agnetha Hilding Qvarnstrom said they were actively involved in the murders, without actually holding the knife.