Kronjäger made her debut in 1985 as Martina under the direction of Peter Grandl in the film drama AIDS – Die schleichende Gefahr.

(1993) for the HFF München, which was released nationwide and attracted a total of 1.2 million viewers, she played the lead role of the lively and daring nurse Maischa alongside Katja Riemann.

In 1997, Peter Wekwerth cast her in his everyday drama Schlank bis in den Tod, in which she played the anorexic Teresa Bille alongside her then-partner Thomas Heinze.

In 2004, she again acted alongside Thomas Heinze in the twelve-part ZDF television series Typisch Mann!, playing the role of Nina Wolf.

In the ZDF Saturday crime series Kommissarin Heller, she took on a recurring role as lawyer Silvie Verhoeven from 2013 to 2021, alongside Hans-Jochen Wagner.