After being educated at an Ursulines convent school in Fritzlar from 1794 to 1797, Bettina lived for a while with her grandmother at Offenbach am Main and from 1803 to 1806 with her brother-in-law, Friedrich von Savigny, the famous jurist, at Marburg. She formed a friendship with Karoline von Günderrode. The two friends acknowledged only natural impulses, laws, and methods of life, and brooded over the “tyranny” of conventionalities. In 1806, Günderrode committed suicide on account of a passion for the philologist Georg Friedrich Creuzer. In 1807 at Weimar Bettina made the acquaintance of Goethe, for whom she entertained a significant passion, which the poet did not requite, though he entered into correspondence with her. Their friendship came to an abrupt end in 1811, owing to Bettina’s behaviour with Goethe’s wife.

In 1811, Bettina married Achim von Arnim, the renowned Romantic poet. The couple settled first at the Wiepersdorf castle, and then in Berlin. They had seven children.

Achim died in 1831, but Bettina maintained an active public life. Her passion for Goethe revived, and in 1835, after lengthy discussions with the writer and landscape gardener Hermann von Pückler-Muskau, she published her book Goethe’s Correspondence with a Child (German: Goethes Briefwechsel mit einem Kinde), which purported to be a correspondence between herself and the poet. The book is in large part fictitious. Genuine sonnets of Goethe in it were addressed, not to her, but to Minna Herzlieb. As a work of fiction, the book has been praised.

After the 1831 death of her husband, Bettina continued her dedication to the creative community. She published a collection of seven songs in public support of Prussian music director Gaspare Spontini, under duress at the time.

The German-American settlement of Bettina in the state of Texas was founded in 1847 and named by its progressive, idealistic founders after Bettina von Arnim. Located near the juncture of Elm Creek and the Llano River, it lasted only a year. No trace of the Bettina community survives, though two of its three founders subsequently became prominent: Gustav Schleicher, later a U.S. congressman and namesake of Schleicher County, and Dr. Ferdinand Ludwig Herff, who in 1854 became the first surgeon to use anesthesia in Texas. The community’s third founder was Hermann Spiess.

Part of von Arnim’s design for a colossal statue of Goethe, executed in marble by the sculptor Carl Johann Steinhäuser (1813–1878), was displayed in the museum at Weimar in 1911.

The chamber opera Bettina by Friedrich Schenker, which was premiered in Berlin in 1987, deals with her friendship to Karoline von Günderrode.

From 1991 until 31 December 2001, her portrait was on the German 5-Mark bill.

In 2006, the German government turned Künstlerhaus Schloss Wiepersdorf, the estate of the von Arnims, into a literary institute. The institute contains a museum devoted to the von Arnims’ literary legacy.