Soost was born in East Berlin and grew up in an orphanage. His mother, who died very early, was a German, and his father came to the GDR from Ghana. The biography on his homepage states that Soost became streetdance champion of East Berlin when he was 15 years old, and champion of the GDR when he was 16, but some critics point out that based on his date of birth given in the same biography (1971) this appears very unrealistic: streetdance was not accepted in the GDR and no "official" battles could be held in which Soost could have won a title. However, there is no doubt that Soost in this time was one of the most important people in (East) Berlin's streetdance scene. Even if there were no "official" titles and championships Soost was the undisputed master of streetdance in East Berlin in this time.
He has two children, daughter Chani, who was born in April 2006, and son Carlos, who was born in July 2007
In 2005, he published his autobiography "Neger – Heimkind – Pionier" ("Negro – Orphan – Pioneer"). In this book, among other things, he also writes about his ethnic background and the problems caused by it. Soost describes himself as "Schoki," a childish word for chocolate. In the years after German reunification, he started a career as a professional choreographer and dance teacher. Later, he founded a network of dancing schools under the brand D!s Dance Club. He owns a "Coaching and Casting Center" in Berlin-Mitte. He also produces dance music and develops choreographies for the D!s Dance Clubs and other dancers under the brand D!Nation.
Soost has been choreographer and head of the jury in every season of the German version of Popstars broadcast by ProSieben. He also leads a similar program called MusicStar on Swiss SF DRS. In 2005 he presented Super Illu TV on MDR. 2005/2006 he also worked for ProSieben presenting Lebe Dein Leben! – Live-Coaching mit Detlef D! Soost, before the show got canceled due to TV ratings. On the German music television channel VIVA Soost hosted, presented and led all four seasons (2005–2008) of the casting show DanceStar.
Soost also took part in the ProSieben reality show Die Alm – Promischweiß und Edelweiß in 2004, a show in which several B-rate German celebrities had to live and work on an alm in the Alps, and the audience could vote for a winner. After the regular time of the show, Soost was close to winning, but had to leave the show when it was extended, because he had other work to do. The term "Herr Soosts Hut" refers to this show (see below). In 2007 he won the German version of the Gameshow Marathon on ProSieben.