Michael Sideris was born on August 26, 1964 in Sindelfingen, Germany, and trained at the Westfälische Schauspielschule in Bochum. After graduating, he was engaged at the Schauspiel Bonn from 1988 to 1990, followed by the Hans-Otto-Theater in Potsdam (1991-94). He then began working as a freelance actor.

Michael Sideris played his first television role in 1991 in the series "Sag mal Aah!", where he played the son of the main character in 27 episodes. In the following years he only took on roles sporadically, for example as a PR specialist in the TV crime thriller "Crash" (1998, also known as "Totalschaden") or in a small role in Sebastian Schipper's "Absolute Giganten" ("Gigantic", 1999).

It was only in the 2000s that Sideris took on more roles in movies and television. In 2000, he starred alongside Uwe Ochsenknecht and Ralf Richter as a loyal fan of FC Schalke 04 in the comedy "Fußball ist unser Leben" ("Soccer Rules!"). In the thriller about the German terrorist group Red Army Faction, "Baader" (2002), he played the lawyer Horst Mahler (called Kurt Wagner in the movie) and in the comedy "Samba in Mettmann" (2004) he was a good buddy of Hape Kerkeling's main character. Sideris also had numerous guest roles in series such as "Der Dicke", "Tatort" and "Die Familienanwältin". From 2005 to 2008, he played a pathologist in 12 episodes of "Die Gerichtsmedizinerin". In 2010 he took over the leading role of the farmer Vinzenz Grieshaber in the children's series "Tiere bis unters Dach".

On stage, he appeared at Berlin's Theater unterm Dach (2008/09) and the Volksbühne (2010). Under the title "Carol King. Queen of the Beach", he created musical song recitals with his colleague and partner Katharina Lindner between 2012 and 2014. From 2012 to 2017, Sideris was a guest performer in the play "Bochum" at the Bochum Schauspielhaus.

At the same time, he continued to take on smaller and larger supporting roles in television and movie productions. In Urs Egger's "Der Fall Bruckner" (TV, 2014) he was a lawyer, in the Dresden "Tatort" episode "Der König der Gosse" (2016) he was the murdered head of a homeless charity, in "Der Barcelona-Krimi - Blutiger Beton" (2020) he was a friend of the investigator Xavi (Clemens Schick) who is brutally thrown out of his apartment - to name just a few examples. Sidaris also continued to appear in the children's series "Tiere bis unters Dach".

He played a leading role in Christoph Hochhäusler's "Bis ans Ende der Nacht" ("Till the End of the Night"), which premiered in competition at the 2023 Berlinale. In the film, Sidaris plays a criminal who is targeted by an undercover cop with a female partner, leading to an unusual love triangle.