In her youth, Marx attended the Dalton School in New York City. She studied at L'Ecole des Sciences Politiques at La Sorbonne in Paris during her junior year of college, and received a B.A. cum laude in Political Science from Bryn Mawr College in 1951. She married the artist Earl Hubbard, whom she met while in Paris, that same year. As of 2003, she is the mother of five and grandmother of six.

She has written five books, delivered more than 80 keynote speeches and given more than 75 interviews. She is currently President of the Foundation for Conscious Evolution, which she co-founded with Sidney Lanier in 1992.

Hubbard was featured in the 2006 film Entheogen: Awakening the Divine Within, a documentary about rediscovering an enchanted cosmos in the modern world.

Hubbard believes that humanity, having "come to possess the powers that we used to attribute to the gods", is presently in a critical and dangerous "Late Transition" to "the next stage of human evolution" which began in 1945 with the atomic bombings of Hiroshima and Nagasaki. She promotes the idea of Conscious Evolution, defined as "evolution of evolution, from unconscious to conscious choice" or "an awakening of a 'memory' that resides in the synthesis of human knowing, from spiritual to social to scientific", as "the only solution" for avoiding global destruction and entering into a utopian "future of immeasurable possibilities."