Karl attended the renowned Hugo Treffner Gymnasium in Tartu.

Ast supported the Russian Revolution of 1905 and was imprisoned in Riga for a period from 1907 to 1910 as a result of his criticism of the authoritarian regime of the Tsar.

With the attainment of independence of the Republic of Estonia, Karl Ast entered politics.

During the Second World War, Karl Ast emigrated from Europe, settling in Brazil, then in Canada and eventually in the U.S.

His short stories made him one of the most popular exile writers of his time.