Sebastian's most famous part was the role of Benjamin in the play adaption to The Graduate.

Sebastian Schlemmer was cast in a minor recurring role as a character named Florian Müller.

One year later, he was part of the casting show Bully sucht die starken Männer for the role of Tjure.

After guest roles on the action series 112 – Sie retten dein Leben and sketch comedy 4Singles, Schlemmer returned to Verbotene Liebe.

He was recast in the role of Sebastian von Lahnstein, a part a took over from fan-favorite Joscha Kiefer, after he decided to leave the show after two years.