He published his debut novelKłopoty to moja specjalność, czyli kroniki socjopaty in February 2007 to a critical acclaim in the Polish press and in Newsweek. Its main character, Tomasz Płachta, is a master in complicating not only his life, but also the lives of people around him. The sequel to this novel, Socjopata w Londynie, published in August 2007, follows the life of Tomasz in London. In July 2008 his third novel, Klub samobójców was published. In a review of the book, Piotr Kofta wrote: 'Koziarski's new book shows that the Polish popular literature now chooses topics so far covered by the "high literature"'. Koziarski also wrote a storyDziewięć żyć kotaAlberta for an anthology that appeared in October 2008; he is now working on the third and final book of his 'Sociopath' series.