Reinhold Hanning was convicted of having assisted in the deaths at the concentration camp in Nazi-occupied Poland between 1943-44.
"You spent nearly two and half years in Auschwitz and therefore you helped in the mass murder," said Judge Anke Grudda during sentencing, according to CNN Affiliate ARD.
The court then sentenced the 94-year-old man to five years in prison, or about 15 minutes per life.
Hanning denied being directly involved in the killings.
Doctors determined him fit to stand trial, but only for two hours a day, on account of his age, a court official said previously.
His legal team have one week to appeal the verdict.
A number of Auschwitz survivors had been set to testify at the trial, the official said.
The attorney general of the German state of North Rhine-Westphalia is prosecuting the case as authorities seek to bring surviving alleged war criminals to justice.
Last push for justice
Hanning's trial is one of a number of criminal proceedings in recent times dating from the Holocaust as German authorities push to hold the last living Nazis accountable before their deaths.
Two other cases are set to appear in German courts in the coming months, including a 95-year-old former medical attendant at Auschwitz
accused of being an accessory to at least 3,681 murders.
At least 1.1 million people were killed in the camps at Auschwitz, the vast majority of them Jewish victims of the Nazi genocide, but also Poles, gays, disabled people and other persecuted minorities.