Liefers is the son of director Karlheinz Liefers and actress Brigitte Liefers-Wähner. After his apprenticeship he studied at theHochschule für Schauspielkunst Ernst Busch in Berlin. From 1987 until 1990 he acted at the Deutsches Theater Berlin; after this he moved over to the Thalia Theater in Hamburg. His first role in cinema was Alexander von Humboldt in the German film Die Besteigung des Chimborazo.
Following that he played in some minor film roles however, in 1996, he achieved his breakthrough with the Helmut Dietl film Rossini – oder die mörderische Frage, wer mit wem schlief. He received the Bayerischer Filmpreis for his role (Bodo Kriegnitz). As a result of this success he was awarded roles in several German films. He has been playing a pathologist in the famous serial Tatort since 2002.
Jan Liefers is a keen motorcyclist and in 2007 started on a trip of a lifetime from Quito (Ecuador) to Patagonia in South America. Unfortunately his trip came to a premature end when he hurt himself avoiding a collision with a young child who ran out in front of his motorbike. In 2008 a film of the trip called «70° West – Entscheidung in Peru» (Decision in Peru) was shown on German TV channel DMAX.