He spent his youth in the Bavarian capital before his father became head of the Imperial Archive (the Reichsarchiv) and the family moved to Potsdam in Prussia.

He had initially welcomed Hitler's seizure of power, but began to distance himself from the new government as he became more aware of its brutality.

In 1942, while being promoted to lieutenant colonel and then to Head of Staff of the 24th Army Corps at the Eastern Front, Quirnheim strengthened his ties to the Resistance through his brother-in-law Wilhelm Dieckmann.

Within hours, Quirnheim, Stauffenberg, Olbricht, and Werner von Haeften had been arrested, summarily tried by Colonel-General Friedrich Fromm—a quiet supporter who betrayed them once he saw the plot had failed—and taken into the courtyard of the Bendlerblock, where they were shot by a firing squad.

A few days later, Quirnheim's parents and one of his sisters were arrested by the Gestapo and his brother-in-law Wilhelm Dieckmann was executed on 13 September 1944.