The man, whom local media have identified as Josef S., was convicted last Tuesday of more than 3,500 counts of accessory to murder and sentenced to five years in prison.
He had denied working as an SS guard at the Sachsenhausen camp and aiding and abetting the murder of thousands of prisoners.
But the Neuruppin state court concluded that he did in fact work at the camp on the outskirts of Berlin between 1942 and 1945 as an enlisted member of the Nazi Party's paramilitary wing.
Prosecutors had based their case on documents relating to an SS guard with the man's name, date and place of birth, as well as other documents.
The five-year prison sentence was in line with the prosecution's demand. The defendant's lawyer had sought an acquittal.
The Neuruppin court said on Monday that the defendant has now filed an appeal. It was not immediately clear when it might be considered.
