Johannes Allmayer was born in Filderstadt in 1978. He studied acting at the Bayerische Theaterakademie August Everding in Munich, followed by engagements at local theatres and a stint at the Bayerische Staatsschauspiel. In 2003, he became an ensemble member at the Schauspielhaus Düsseldorf, where he featured in stagings of "Woyzek", "Peer Gynt" and "Ein Sommernachtsraum". Around that time, he also got his first TV roles, and in 2004, he made his movie debut opposite Anna Brüggemann in the drama "Stages". In 2007, he played a lonely call center agent in André Erkau"s award-winning "Selbstgespräche", and the following year, he was cast in Matti Geschonneck"s two-part TV thriller "Entführt".

Apart form his TV work, Allmayer had memorable supporting roles in the lauded box office hit "Vincent will Meer" (2010) and Hans W. Geissendörfer"s drama "In der Welt habt ihr Angst" (2011). He was again cast by André Erkau as one of the leads of the comedy "Arschkalt", which was released in Summer 2011. The same year, he was also featured in the ensemble cast of the comedy "Kein Sex ist auch keine Lösung".