The 26-year-old Jordanian, 1st Lt. Mu'ath al-Kaseasbeh, was taken captive after his F-16 fighter jet crashed near the extremists' de facto capital of Raqqa in northern Syria. He was forced into a cage that was set on fire in early 2015.
The suspect, identified by Swedish prosecutors as Osama Krayem, 32, is alleged to have traveled to Syria in September 2014 to fight for IS.
Krayem was sentenced to life in prison on Thursday, Swedish news agency TT reported.
Krayem was indicted by Swedish prosecutors in May on suspicion of committing serious war crimes and terrorist crimes in Syria. He was previously convicted in France and Brussels for fatal Islamic State attacks in those countries.
The airman became the first known foreign military pilot to fall into the militants' hands after the U.S.-led international coalition began its aerial campaign against the Islamic State group in Syria and Iraq in 2014.
Jordan, a close U.S. ally, was a member of the coalition and the pilot's killing appeared aimed at pressuring the government of Jordan to leave the alliance.