Berkowitz was born to concertmaster and conductor Victor Wassiljew and his wife, a singing teacher. The family had emigrated in 1923 from the Soviet Union to Berlin. Shortly after her husband's death, Liane's mother married Henry Berkowitz, who adopted Liane. Berkowitz saw to it that Liane could prepare herself for her Abitur by going to a private Gymnasium as of 1941.
At the Heil'sches Gymnasium in Berlin, she met Dr. John Rittmeister's wife Eva Knieper, Fritz Thiel and Friedrich Rehmer. She became engaged to Rehmer late in 1941 while they were working together in the "Rittmeister Group" with the Red Orchestra resistance group against the Nazi régime.
On the evening of 17 May 1942, Berkowitz, along with Otto Gollnow, was given the task of putting up about 100 posters in the Kurfürstendamm-Uhlandstraße section of west-central Berlin which protested against the Nazi "Soviet Paradise" propaganda exhibition being held in the city. They were carefully and unobtrusively guided and protected throughout this exercise by Harro Schulze-Boysen.
For this act, Liane Berkowitz was arrested on 26 September 1942 and charged. Friedrich Rehmer, who was in the Brietz military hospital recovering from a severe war wound sustained on the Eastern Front was arrested on 29 November 1942 and taken from the hospital. The Second Senate of the Reich Military Tribunal sentenced Berkowitz and Rehmer, along with 16 other people from the Red Orchestra, to death on 18 January 1943 for abetting a conspiracy to commit high treason and furthering the enemy's cause.
It was, however, the Tribunal's recommendation that Berkowitz be released from custody because she was pregnant, but Adolf Hitler expressly forbade this, having Field Marshal Wilhelm Keitel uphold and countersign the death sentence.
Along with 11 other women, Berkowitz was executed at Plötzensee Prison on 5 August 1943. Her daughter Irene, born while she was in custody at the Barnimstraße Women's Prison, died at Eberswalde Hospital two months later under unclear circumstances.
Liane Berkowitz lived at Viktoria-Luise-Platz 1 in Berlin-Schöneberg, where a memorial plaque to her may now be found. In the year 2000 a plaza in Berlin was named after her (Liane-Berkowitz-Platz).