She first became known as a teenager for her main role in Chris Kraus' 2010 film Poll.

Her breakthrough came in 2016, when she starred in François Ozon's Frantz, for which she won the Marcello Mastroianni Award for Best Young Performer at the 73rd Venice International Film Festival.

In 2018, Beer starred in Florian Henckel von Donnersmarck's Never Look Away, which was nominated for Best Foreign Language Film at the 91st Academy Awards.

In the following years she became internationally known for her performances in Christian Petzold's films, starting with Transit (2018).

She also starred 2023's Afire, which won the Silver Bear Grand Jury Prize at the 73rd Berlin International Film Festival.