Michael Maertens was born in Hamburg in 1963 into a famous theatre family. After attending the Otto-Falckenberg Hochschule für Schauspielkunst in Munich, he joined the ensemble of Hamburg's Thalia Theater in 1989. In his first season, he received the Boy Gobert Award for his role in CLAVIGO and was named Young Actor of the Year. He has also performed at the Schiller Theater and the Deutsches Theater in Berlin, the Münchner Kammerspiele, the Berliner Ensemble, the Deutsches Schauspielhaus in Hamburg, the Maxim Gorki Theater in Berlin, the Schauspielhaus Bochum and the Burgtheater in Vienna. During Barbara Frey's tenure as artistic director, he played numerous leading roles at the Schauspielhaus Zürich. He has worked with directors such as Peter Stein, Luc Bondy, Jürgen Flimm, Dieter Dorn, Claus Peymann, Klaus Maria Brandauer, Martin Kušej, Matthias Hartmann, Thomas Langhoff, Benno Besson, Jürgen Gosch, Jürgen Flimm, Katharina Thalbach.
In 2001 he was named Actor of the Year by THEATER HEUTE. He was awarded the Gertrud-Eysoldt-Ring in 2002 and the Nestroy for Best Actor in 2005, 2022 and 2023. In 2017, he was named a Kammerschauspieler, a title awarded by the Austrian Federal President to outstanding actors. Michael Maertens also makes regular appearances in film and television productions, including SONNENALLEE, DIE VERMESSUNG DER WELT, VORSICHT VOR LEUTEN, FINSTERWORLD, BIBI & TINA, FACK JU GÖHTE 2 & 3, TAUSEND ZEILEN or DAS PUBERTIER. In December 2023, the Til Schweiger film DAS BESTE KOMMT NOCH with him and Til Schweiger in the leading roles was released In 2014, he was awarded the German Actor's Prize at the Berlin Film Festival in the category ‘Best Actor in a Supporting Role’. He recently received his third Nestroy Award. In the summer of 2023, he took on the title role in the play JEDERMANN at the Salzburg Festival.