Marcel Klett was born in Wuppertal in 1970. He studied German language and literature, general literary studies and linguistics of German at the University of Wuppertal and completed training in business administration at the Fernuniversität Hagen. From 1995 to 2000 he worked as a dramaturge and director in the independent theater scene of North Rhine-Westphalia. After an engagement as dramaturge at the Schauspiel Wuppertal, he moved to the Theater in der Fabrik of the Staatsschauspiel Dresden in 2001. There he worked as a dramaturge and scheduler. From 2002 to 2004 he took over the provisional artistic direction of the Theater in der Fabrik.
Subsequently, Marcel Klett was artistic director (together with director Markus Heinzelmann) and senior dramaturge at Theaterhaus Jena. He was also a shareholder of the theater until 2010. From 2007 to 2012 he was employed at the Theater Bremen as head of drama. Between 2010 and 2012, he was a member of the five-member board of directors that replaced the theater's artistic directorate. From 2013 – 2018, Marcel Klett returned to Theaterhaus Jena as commercial director and member of the artistic board, before moving to Maxim Gorki Theater as managing director in the 2018/19 season.