Ernst Kernstock (5 August 1852 in Graz – 14 April 1900 in Klagenfurt) was an Austrian schoolteacher and lichenologist.
While a student, he worked as an assistant in the botanical laboratory at the University of Graz.
After receiving his qualification as a teacher of natural history, mathematics and physics in 1877, he worked for many years as an instructor in Bolzano (1877–1895).
From 1895 onward, he taught classes at the Realschule in Klagenfurt.
His herbarium was obtained by the Natural History Museum in Vienna.