Born in Bucharest, Lara is the only of child of Valentin Plătăreanu, a Bucharest actor, and his wife, Doina, a homemaker. At the age of four (in 1983) her family decided to flee to West Germany to escape from the Nicolae Ceauşescu regime in Communist Romania. Although the family had originally planned to emigrate to Canada, they settled down in Freiburg im Breisgau, Baden-Württemberg, before eventually moving to Berlin.

After graduating at the Französisches Gymnasium Berlin in 1997, Lara went on studying acting under the management of her father, co-founder of the Theaterwerkstatt Charlottenburg, until 2000.
By the age of 16 she was already playing lead roles in various television dramas. Since then her career has developed and she has become a respected film actress.

Her most famous role to date, which has resulted in international recognition, is as Traudl Junge, Adolf Hitler`s secretary in the Oscar Nominated 2004 film Der Untergang.

Due to her convincing performance in Der Untergang, Francis Ford Coppola wrote her a letter and gave her a leading role in Youth Without Youth (2007).

She plays a lead role in legendary Greek director Theo Angelopoulos` 2007 film The Dust of Time, opposite Harvey Keitel and Bruno Ganz.

Also in 2007, she appeared as journalist Annick Honore in the film Control, the Ian Curtis biopic.