Demjanjuk was convicted of being an accessory to mass murder in his capacity as a guard at the Sobibor concentration camp, where he led the Jews to the camp's gas chambers, The Guardian reported.
Demjanjuk, sitting in a wheelchair, showed no reaction when the verdict was announced.
The British publication said it wasn't clear how much credit Demjanjuk would receive for time served.
During the 18-month trial in Munich, his defense team said it would would appeal a conviction.
Demjanjuk, a Ukrainian, was a Red Army soldier allegedly captured by the Germans in 1942 and trained as an SS guard before being sent to work at the camp.
Demjanjuk, who fled to the United States and worked in an auto plant near Cleveland for decades, was described by one Nazi expert as "the littlest of the little fishes" and is the lowest ranking person to be tried for war crimes in Germany, The Guardian said.
The prosecution presented no evidence tying Demjanjuk to a specific crime but said his presence at the camp was enough to charge him with being an accessory to murder.
Prosecutors alleged Demjanjuk was one of the guards who forced Jewish prisoners into rooms, knowing engine fumes were to be pumped in. He also allegedly removed corpses and threw them into a mass grave.
Demjanjuk maintained his innocence, saying he was a victim of Nazi crimes.
"Should foreigners pay for the crimes of the Germans in order to acquit Germany of its responsibility alone for the Holocaust?" defense attorney Ulrich Busch said.
Demjanjuk, who changed his first name from Ivan to John when he arrived in the United States, spent more than seven years in an Israeli prison after being found guilty of being a guard known as "Ivan the Terrible" at the Treblinka concentration camp. He was released when a case of mistaken identity was proven.
Demjanjuk, who fled to the United States in the 1950s, spent 10 months in a jail while awaiting extradition to Germany. He was deported in 2009.