Williamson has written several self-help books, including A Return to Love: Reflections on the Principles of A Course in Miracles in 1992, which became a New York Times Best Seller.

[1] Williamson ran unsuccessfully as an independent for California's 33rd congressional district in the United States House of Representatives in 2014, finishing fourth with 13.2% of the vote.

[5] Williamson's presidential platform calls for an end to the war on drugs, a federal minimum wage increase, reparations for racial injustice, addressing climate change, and creating a U.S. Department of Peace.

[11][12] Williamson has been actively involved with charity work, founding such organizations as Center for Living in 1987, Project Angel Food in 1989, and the Peace Alliance in 1998.

She is the youngest of three children of Samuel "Sam" Williamson, a World War II veteran and immigration lawyer, and Sophie Ann Kaplan, a homemaker and community volunteer.

[19] After graduating, she spent two years studying theater and philosophy at Pomona College in Claremont, California, where she was a roommate of future film producer Lynda Obst.

[18] After leaving Texas, she went to New York City, intending to pursue a career as a cabaret singer; however, she has stated that she was distracted by "bad boys and good dope".

[22] Williamson said the book was her "path out of hell", as she had been "mired in a series of unhappy love affairs, alcohol and drug abuse, a nervous breakdown, and endless sessions with therapists.

[30] In 1979, Williamson returned to Houston, where she ran a metaphysical bookstore coffee shop, sang Gershwin standards in a nightclub, got married and divorced "almost immediately", and underwent a "spiritual surrender".

[32][22] As word spread about "the young woman talking about a God who loves you, no matter what," she had to rent church space to accommodate the demand to hear her speak.

The book appeared on The New York Times bestseller list for 39 weeks in the "Advice, How To and Miscellaneous" category;[44] it teaches that practicing love every day will bring more peace and fulfillment to one's life.

[49] Prominent elected and public officials endorsed her campaign, including Ben Cohen; former governors Jennifer Granholm and Jesse Ventura; former representatives Dennis Kucinich and Alan Grayson; and Van Jones.

[70] The spike in searches was prompted by her reference to the Flint water crisis and her assertion that President Trump was harnessing a "dark psychic force of the collectivized hatred," which she later described as racism, bigotry, antisemitism, homophobia, Islamophobia, and xenophobia propelled by social media.

[73] Many pundits treated Williamson's brief campaign as comic relief, often characterizing her as a novelty candidate due to her unconventional approach and spiritual rhetoric.

After the July 30, 2019, Democratic debate, New York Times columnist Jamelle Bouie wrote, "It feels insane to say this, but Williamson out-debated virtually everyone else on the stage.

[78] Earlier in 2023, a dozen former staffers from her 2020 campaign, who remained anonymous due to having signed non-disclosure agreements (NDAs), described working for Williamson as "toxic," "traumatic," and "terrifying".

According to one account, her anger over logistics in South Carolina led her to strike a car repeatedly to the extent that she had to receive medical attention for a swollen hand.

[95] Williamson supports the distribution of $200-$500 billion in reparations for slavery, spread across 20 years for "economic and education projects", to be disbursed based on the recommendation of a selected group of black leaders.

[13][104][105] Williamson has stated her support for the necessity and value of vaccinations and antidepressants,[106][107] but has been criticized for her skepticism about the pharmaceutical industry's influence in setting guidelines for how they are administered, citing her belief that their profit motive could result in harm to patients.

[112][107] During Williamson's presidential campaign, several excerpts of her past comments have conflated her skepticism of the pharmaceutical industry's trustworthiness with an embrace of anti-vaccination dogma.

[115] In June 2019, Williamson criticized then-President Donald Trump on his immigration policies after reports of children being separated from their families and being put in a detainment center; she called these acts "state-sponsored crimes".

[117] Williamson also supports Deferred Action for Childhood Arrivals (DACA) and expanding protections and naturalization to undocumented immigrants who were brought to the United States as children, regardless of their current age.

[118] Williamson supports The Equality Act[119] and an increase of the federal minimum wage to $15 per hour,[120] and has called religion a map in which "the route isn't important.

[122] Williamson supports military engagement when a NATO ally is threatened, when the United States is under threat of attack, or "when the humanitarian order of the world is at risk".

[99] Williamson has said she supports the U.S. vigorously using its position, i.e., through CFIUS, to prevent China from buying strategically important companies, which she believes will help defend U.S. economic interests and human rights, as in the cases of the Uighurs and residents of Hong Kong.

[55][124][125] “and ‘activist’ [126]and has been called ‘populist adult educator’,[127] and ‘philosopher’,[128] and ‘mystic’,[129] she has “always viewed things through a mystical lens,” Williamson told a crowd during her 2020 presidential campaign, and invoked the David and Goliath biblical story as her own (with her followers) saying “We’re going to get him [Donald Trump] right between the eyes...his third eye”;[130] she also self-identifies as a ‘metaphysician’ [131] and concluded once declaring about the American population that “We’re hallucinating....a mass hallucination” [132] of a distorted reality.

[134][135] She made headlines when she criticized Vogue for its "insidious influence" when it did not include her in an Annie Leibovitz photo shoot of the 2020 female presidential candidates.

[21] The Center provided services such as housework, daily chores, meditation, massage, psychological counseling, and emotional support throughout the city and county of Los Angeles.

[152][153] In 1998, Williamson co-founded the non-profit Global Renaissance Alliance (GSA) with Conversations with God author Neale Donald Walsch.

A critical discussion of Marianne Williamson’s approach to the presidency campaign and her philosophy in the current context of politics appeared on the podcast site called Integral Stage [163] in 2023.