After his graduation, Karasek started working as a journalist, and in 1968 became the theatre critic of the weekly newspaper "Die Zeit". From 1974 until 1996 he wrote for the news magazine "Der Spiegel", where he worked as the chief editor of the feuilleton. After his retirement from "The Spiegel" he wrote a novel named "Das Magazin" in which he criticised "Der Spiegel". He also worked in later years for newspapers like "Die Welt", "Bild", "Berliner Morgenpost" and "Der Tagesspiegel". He also wrote more than 20 books about his own life or literature and film, including monographs about Max Frisch, Bertolt Brecht and his close friend Billy Wilder. Other projects included three plays under the nom de plume Daniel Doppler and a translation of Raymond Chandler's The Lady in the Lake. In 1999, he was a member of the jury at the 49th Berlin International Film Festival.