Claver Berinkindi, a Swedish citizen, had been found guilty of genocide and gross violation of international law in May 2015.
He appealed the ruling, saying he was innocent.
Berinkindi came to Sweden as a refugee in 2002 and became a Swedish citizen 10 years later.
Rwandan authorities initially wanted to prosecute him in Rwanda but since he's a Swedish citizen he couldn't be extradited.
Some 800 000 people, mostly ethnic Tutsis and moderate Hutus, were killed by Hutu extremists during the genocide, according to the UN.