Dorothea's paternity is disputed but generally assigned to Count Aleksander Batowski, a Polish envoy to the Duchy of Courland.

The fall of the First French Empire and the Congress of Vienna, at which Charles-Maurice de Talleyrand was designated to represent France, favoured a close friendship between him and Dorothea.

Despite having been his companion (he was 39 years her senior) she took several lovers, gaining a reputation as a formidable seductress and bearing three illegitimate daughters (one of whom, born in 1816, was perhaps Božena Němcová, the great Czech writer, fathered by Count Karel Jan Clam Martinic, her lover at the Congress of Vienna; the two others, Julie Zulmé and Antonine Piscatory, were born in 1826 and 1827).

When Talleyrand became French ambassador in London in 1830, she accompanied him and felt more comfortable there than in Paris, which she detested and where the whole Faubourg Saint-Germain made her feel she was a foreigner.

On 6 (or 8) January 1845, the king of Prussia invested Dorothea as duchess of Sagan (with the special privilege of the dukedom being able to descend via the female as well as the male line), with her son Louis-Napoléon, godson of Napoleon and Louis-Napoléon's grandson Boson de Talleyrand-Périgord immediately taking the title of prince of Sagan.

Despite the wish she had expressed to her uncle Talleyrand in a letter of April 1838 and in her will, that her heart should be placed in his grave at Valençay, she was buried in the Kreuzkirche at Sagan, with her sister Wilhelmine and son Napoléon Louis.

The opinions she inspired are various; those of men, admiring her beauty and intelligence, praise her, but those of women, jealous of her position and wealth, are more venomous.

Born between two cultures, speaking three languages, in contact with all the political personalities of Europe, she could have been, in another era, thanks to her intelligence, a scholar or politician.