Following her studies, she worked as a lecturer and researcher at the National Institute of Philosophy in the Academy of Sciences of East Germany.

She was the co-founder of Pankow Peace Circle [de] in the autumn of 1981, the Environment Library Berlin; Profession group and the Church from Below in 1986.

Due to her public protests against the stationing of Soviet nuclear missiles in East Germany, she was expelled from the SED in 1983 and her profession.

In January 1988 she was arrested in advance of the demonstration in honour of Liebknecht and Luxemburg in East Berlin carrying a poster declaring "Every citizen has the right to express his opinion freely and openly" (Article 27 of the Constitution of East Germany) and detained in Berlin Hohenschönhausen prison.

[2] She was put on trial by the city district of Lichtenberg on the grounds of "attempted riotous assembly" and although given a custodial sentence she was instead allowed the option of leaving the GDR on a temporary visa[3] effectively deporting her from the country.

In 1991 she protested the Gulf War by keeping quiet during her allotted speech time in the Bundestag until she was cut off.

[4] In August 2009 she produced election posters featuring photos emphasizing her cleavage along with a picture of Angela Merkel in a very low-cut dress, emblazoned with the slogan We have more to offer.

[5] Lengsfeld has opposed immigration into Germany, and helped to organize the Erklärung 2018 declaration and petition in opposition to it.

She forgave him in 2000 when he was gravely ill.[2] Lengsfeld's father retired from the Stasi in 1986 rather than obey an order to break with his daughter; in 1988 he publicly took her side.