Riemelt started his career "by coincidence, because" he "had not really thought about getting involved in acting and had not joined any drama groups at school". He decided early on that he was not interested in the latter: "I have an aversion to drama schools because their methods seem suspect to me. The way they treat people is sometimes inhuman, they build people up and then break them. Some people can cope with this, but I don't want to risk that".
He explains that he feels "much happier in front of a camera than acting on a stage. I am a minimalist as far as my approach to acting is concerned" and prefers working for cinema, although "I am prepared to work for television if it is an interesting project, there is a good script and the characters are good."
Similarly, he welcomes the chance every now and then to act in student films "because it gives me the chance to try out things and bring in my own ideas and often create quite different characters from the ones they had originally planned".
He has starred in all of Dennis Gansel's feature films, starting with Mädchen, Mädchen.