Kerner is an occupational surname of German and Jewish (Ashkenazic) origin.
There are various possible derivations, including as a name for a farmer or a nickname for a small person, from a Middle High German kerne ("kernel seed pip"); German Kern or Yiddish kern (grain), among others.
Middle English kerner is a variant of cherner ("churner; one who churns butter").
[1] It may also derive from "carter" or "carrier", from the German word kerenere.
The name was found in Bavaria, Germany, in the medieval period.