Oskar Laske was born on January 8th 1874 as the son of an architect in Czernowitz. In his high school days he received artistic training by the landscape painter Anton Hlavacek. He went on to study architecture at the Technical University of Vienna and at the academy of visual arts, where Otto Wagner was his teacher.

First a freelance architect, Oskar Laske mainly worked as a painter from 1904. Except for the painting education in his youth, he was a self-taught artist. Even before World War I, he travelled to various countries in Europe, the Middle East and North Africa, painting landscapes and people. 

During World War I, he was an officer in Galicia and at the front of Isonzo. Then he became a k. u. k. (imperial and royal) war painter. Numerous war paintings bear witness to his experiences at that time. In 1907 Laske joined the Hagenbund and in 1924 the Vienna Secession. His work was not only exhibited at those artist associations but also internationally.

After the Anschluss of Austria to Nazi Germany Laske continued painting. In 1939 he became a member of the Künstlerhaus, however he retreated into an „inner emigration“, paintig being the only way for him to come to terms with what he experienced during the war.

In his final years he was an established artist and mainly dedicated himself to smaller works, etchings and watercolors. Oskar Laske died in 1951 at the age of 77 in Vienna. He left a distinguished oeuvre, which was honoured in numerous retrospectives.