Despite confirming the verdict of an earlier court, the appeals court acquitted the man of some of the crimes he had earlier been found guilty of, including nine counts of murder and four of attempted murder.
In June last year, a Stockholm court found the man guilty of genocide crimes and crimes against the law of nations, including murder, attempted murder, and kidnapping. That court sentenced the 50-year-old to a lifetime in jail, a sentencing upheld by the appeals court.
According to the United Nations some 800,000 people, mainly minority Tutsis, were killed in the Rwandan genocide, which began after the assassination of Rwanda's Hutu president Juvenal Habyarimana in April 1994.
Rwandans who took part in the genocide have also been sentenced in the United States, Canada, Finland, Norway, the Netherlands, Switzerland and France for their role in the killings.
Sweden has previously sentenced to life imprisonment two other naturalized Rwandans in 2014 and 2016 respectively, for their roles in the genocide.