The 28-year-old man who allegedly pushed the woman into the oncoming train was held by eye witnesses and handed over to the police, Spiegel reports.
The young woman died of her injuries at the scene.
Police say that the incident happened on Tuesday evening at Ernst Reuter Platz, on the U2 line in the west of the capital.
The background to the incident is still unclear, but police currently believe the victim did not know her assailant. They are now looking for further eyewitnesses.