Felka Platek was born in Warsaw when it still belonged to the Russian Empire, and she lived with her parents in a Jewish quarter of the city. She moved to Berlin in 1923/24 to begin her studies, and attended the Lewin-Funcke School in Charlottenburg to learn portrait painting. It was in 1924/25, in the class of Ludwig Meidner, that she met her later husband Felix Nussbaum. When Nussbaum won a scholarship to stay in the Villa Massimo in Rome, Platek moved there with him in October 1932. In May 1933, an incident occurred that was to have serious consequences for both of them. The painter Hanns Hubertus Graf von Merveldt also had a scholarship to stay in the Villa, and an argument between him and Nussbaum ended in fisticuffs. Merveldt, Platek and Nussbaum were thereupon all expelled from the Villa Massimo.
Platek and Nussbaum then spent one and a half years on the Italian Riviera. The ominous political developments in Germany prompted them to emigrate to the Belgian seaside resort of Ostend in 1935, where many German emigrants were living. They married in Brussels in 1937 and moved into an apartment there. Living conditions became more difficult for Platek and Nussbaum once the Nazis forced them to wear the Star of David on their clothes, and they were compelled to abandon their apartment in 1942. In late May/early June 1943, Felka Platek and Nussbaum manged to find a basement apartment in which to hide, but they were discovered on 20 June 1944 and sent to the Mechelen transit camp. Felka Platek was in the last deportation train that left for Auschwitz, on 31 July. She was murdered there in August 1944.