Ulrike Meinhof's parents both died early, leaving Ulrike and her sister Weinke in the care of Renate Riemack, a friend of their mother's. Riemack was a devoted socialist, and a profound influence on Meinhof.

Meinhof married Klaus Rainer Röhl, publisher of the left-wing student newspaper, konkret. After a few years Meinhof became konkret's editor. Röhl and Meinhof had twin girls, Bettina and Regine, on 21 September, 1962.

Meinhof drifted away from Röhl, and towards the radical fringe of the student movement. She left her husband in the late sixties. On 14 May, 1970, she participated in the freeing of Andreas Baader, giving birth to the so-called "Baader-Meinhof Group." Though partially named after her, Meinhof was not, as is often assumed, the co-leader of the gang (Baader, along with his girlfriend Gudrun Ensslin, led the group, with Meinhof, Jan-Carl Raspe, and others comprising a second tier of leadership). She spent the next two years on the run, robbing banks and bombing buildings, before being captured on 15 June, 1972.

While in prison over the next four years, Meinhof grew increasingly depressed as the other members ostracized her. She "comitted suicide" in her cell on 9 May, 1976, though many have questioned this official explanation and instead suspect that she, like Baader, was murdered by the state.