Martha Nibley was born in Provo, Utah in 1962, one of eight children of Hugh and Phyllis Nibley, and raised as a Mormon in a prominent family. She received an BA degree in East Asian studies, along with an MA and a Ph.D. in Sociology from Harvard University.

Beck met John Christen Beck, a fellow Mormon from Utah, during her undergraduate studies at Harvard. They married in the LDS Salt Lake Temple on 21 June 1983 in Salt Lake City, Utah, and eventually had three children together.

After the birth of their second child, Adam, who had been diagnosed with Down Syndrome prior to his birth, Beck returned with her husband and children to Utah, to be nearer to family and support. Expecting Adam: A True Story of Birth, Rebirth and Everyday Magic is Beck's story about her decision to give birth to and raise Adam.

In 1990, soon after the birth of her third child, Beck joined the faculty of Brigham Young University (BYU) in Provo, Utah, teaching a course on the Sociology of Gender in the Department of Social Science. During her tenure at BYU, five faculty members were excommunicated from the LDS church as a consequence of public writings that were deemed critical of the Mormon church. She and husband John Beck also made critical public statements about both the excommunications and other church and BYU matters, which led to first John, then Martha herself, leaving the Mormon church in 1993.

Beck later wrote a book detailing the catalyst for her resignation from the church, Leaving the Saints, in which she alleges having been sexually abused as a child, and the Mormon community's subsequent reaction.

Her first book, coauthored with her husband, John Beck, Breaking the Cycle of Compulsive Behavior treated homosexuality as one of several "compulsive behaviors," like bulimia. However, both Martha Beck and her now ex-husband subsequently came out publicly as gay and have stated that they no longer consider homosexuality a form of compulsive behavior. In 2003, Beck separated from her husband, divorcing from him in 2004. She began living with her partner Karen Gerdes, a social worker and professor, during her marriage and has continued this relationship.

Today, Beck lives in Phoenix, Arizona and is a partner in NorthStar, Inc. a life coaching consulting and seminar company. Beck also writes a monthly column in O-The Oprah Magazine. She has also written several self-help books, including Finding Your Own North Star, a book aimed at providing guidance to finding a purpose in life, The Joy Diet: 10 Daily Practices for a Happier Life, which offers insights into the importance of healthy and happy living habits to a fulfilling life, and Breaking Point: Why Women Fall Apart and How They Can Re-create Their Lives, which analyzes stresses and challenges that modern women face and offers advice on coping with and overcoming these issues.

In 2005, she received national attention for her bestselling book, Leaving the Saints: How I Lost the Mormons and Found My Faith. According to the Mormon magazine, Sunstone,. the book may have originally been conceived as a novel, loosely based on her life (with a male main character), but was changed to recount her personal experiences, with the encouragement of her publishers. Ultimately released in March 2005, the book is a narrative in which Beck describes recovered memories of alleged sexual abuse by her father, prominent LDS academician Hugh Nibley; her experiences teaching at Brigham Young University; cultural dissonance and anomalies in Utah; her spiritual journey leaving the LDS church.Prior to and after publication of the book, several national newspapers in the United States reported that Beck's memoir had quickly become controversial in Mormon circles. Numerous articles were published in response to the book, including a critical essay by the Mormon author of Hugh Nibley's biography, Boyd Jay Petersen. Petersen states in his conclusions, "Throughout this book, as with her other books, it is obvious that she distorts the record as much as or more than she reports it, jumps to conclusions more than provides evidence leading to conclusions, and blurs fact and fantasy. But to stick to the facts requires more than simply assuring readers that you do. You actually have to stick to them, something it seems Martha seldom does." Beck responded to some of these criticisms by stating that she began having memories of her traumatic events prior to the use of any therapy (including hypnosis), that her vagina had scarring that may have been the result of sexual abuse, and that her memories were vivid and intrusive. Family members have also pointed out the impossibility of activities such as Beck described being carried out in the tiny Nibley home, where there was little or no privacy and multiple children shared every bedroom. Some members of Nibley's surviving family also challenge Beck's allegations by pointing out inconsistencies in her descriptions of events to various media sources. Hugh Nibley's family, including Beck's siblings, have claimed the book's accusations against their father are false and have expressed "outrage" at the book and accusations.

Although most of the criticism centered around Beck's allegations of sexual abuse, a substantial portion of the book involves a discussion of the Mormon church and its policies. BYU professor Robert L. Millet criticized her some of her portrayals as "nonsense", "ludicrous", or "paranoia", saying that she "seems to be a magnet for improbable happenings" and "equate[s] weird anomalies in Mormon culture with the norm." The book also mentions that her father may have misinterpreted certain Egyptian hieroglyphics in order to support some of the writings of early church leaders, including Joseph Smith.