Her grandfather was one of Frankfurt's first social-democratic aldermen.
At 14, she joined the Socialist Worker Youth, and at 18 became a member of the Social Democratic Party of Germany (Sozialdemokratische Partei Deutschlands – SPD).
She worked avidly in the women's movement.
In Frankfurt, she became friends with Eleonore Wolf, whose life was taking a similar path.
During the First World War, Kirchner, now a mother of two daughters, busied herself in communal welfare, dedicating herself to needy women's and children's welfare.
After that, she worked in the Workers' Welfare organization (Arbeiterwohlfahrt; AWO), which she founded together with Marie Juchacz in 1919.
Her special concern here was children who were underfed as a result of the war and the widespread inflation that struck Germany later.
Many of these children suffered from damaged health and stunted growth.
They had had their childhood taken away from them by events over which they had no control.
Kirchner took many of these children to Switzerland for their health.
During the Ruhrkampf, a brief civil war in Germany in 1920, Kirchner helped evacuate thousands of children from the Ruhr district, sending them to stay with families in Hesse.
In 1933, Adolf Hitler came to power, and the dedicated anti-fascist had to go underground, as her help in freeing an anti-Nazi from the Gestapo became known, leading to the danger of her possible arrest.
She fled, without her family, to SaarbrĂĽcken, which was then still under League of Nations administration.
Even while abroad, she helped the resistance movement in Germany: she led the Saar Refugees' Committee (SaarflĂĽchtlingskommitee), drew up plans and reports for the SPD's executive in exile, and produced and distributed illegal leaflets.
Even though Kirchner belonged to the SPD and Eleonore Wolf did illegal work for the Communist Party of Germany (KPD), they worked quite closely together in the Saar region as they organized the emigration of many officials of the workers' movement out of the Reich.
These women's solidarity greatly helped Kirchner overcome the ordeal of being thrown in prison.
However, Kirchner's case was brought back before the Volksgerichtshof in 1944.
This time, Roland Freisler, the Chief Justice at the Volksgerichtshof, sentenced her to death, and she was beheaded at Plötzensee Prison in Berlin.
The judgment accused Kirchner of having "treasonably rooted herself in the evilest Marxist high-treason propaganda".
It also accused her of "treasonably gathering cultural, economic, political, and military intelligence and communicating" the same.
"Keep Goethe's words in mind," wrote Kirchner in a letter to her children on the day of her death, "'Die and become'.