To modern audiences, she's probably most famous for her role as Rosa Klebb in From Russia with Love. She originated the parts of Jenny in The Threepenny Opera, Jenny in The Rise and Fall of the City of Mahagonny, Anna in The Seven Deadly Sins, and Fräulein Schneider in Cabaret. She also acted alongside Peter Lorre in Frühlings Erwachen.
In the 1930s, she was forced to escape from Germany and moved to the United States, where she resolved to speak and write English almost exclusively from that point on. She was famously name-checked by Louis Armstrong during his recording of "Mack the Knife", when he saw her standing near him in the studio.
Lenja's correspondence with Kurt Weill was published in book form, titled Speak Low (When You Speak Love). A play based on the collected letters, Lovemusik, opened on Broadway in 2007.