Elsa Blochwitz rejected National Socialism early on. As a young woman, she made critical statements at public NSDAP events. She worked from home in Berlin repairing silk stockings. In 1937 her friend and colleague Margarete Dietrich moved into the apartment with her.
In 1935 Blochwitz took in the Jewish sisters Herta and Käthe Arndt. Käthe Arndt was able to emigrate in 1938. When Elsa Blochwitz was ordered to evict her sub-tenant in 1941, she refused. She was forced to place the yellow star on her own front door. Herta Arndt was deported in November 1941.
Nonetheless, Elsa Blochwitz went on hiding persecuted Jews in her home. Some came to her apartment regularly during the daytime, such as Margarete Nebel and Dora Kanner. During the war, her role as an air raid warden enabled her to shelter Jews in vacant apartments or basement rooms. In 1944 she took Rita Grabowski into her home. She helped a total of more than seventy Jewish people.
Elsa Blochwitz was honored by the West Berlin senate as an Unsung Heroine in 1960 and by Yad Vashem as Righteous Among the Nations in 1965.