A Banat Swabian, Künstler enlisted in the Austro-Hungarian Army at Szeged in February 1918 in a field artillery regiment (HFKR 5. k.u.

Following World War II, Künstler lived in Niederstetten, Baden-Württemberg, West Germany, and worked as a guide in a museum.

In an interview given at the age of 107 to an Austrian magazine, Künstler was asked about "the most important thing in life".

"[4] With the February 2008 death of 107-year-old Georg Thalhofer, who had been physically unfit for World War I service, Künstler became the oldest living man in Germany.

[5] He died of complications from intestinal surgery in Bad Mergentheim after having fallen ill while visiting his native Hungary.