Johnson grew up in Rockdale, Texas, and graduated from Rockdale High School. She obtained her B.S. degree in psychology from Texas A&M University and an M.A. in counseling from Sam Houston State University.
Raised in a "conservative, pro-life family," Johnson began volunteering for Planned Parenthood after seeing their booth at a volunteer fair at her college. She says she hadn't heard of the group before and didn't know they performed abortions, and Planned Parenthood told her they wanted to reduce the number of abortions. Johnson volunteered in 2001, and progressed to the position of community services director. Identifying as "extremely pro-choice," she worked at the Planned Parenthood clinic in Bryan, Texas for eight years, escorting women into the clinic from their cars to prevent them from being heckled by protesters and eventually working as director of the clinic. Johnson regularly encountered activists from Coalition for Life, a local anti-abortion group who waited at the clinic's fence to talk to clients, and described extensive harassment of clinic staff by anti-abortion activists. Describing death threats against herself and her family, she stated: "It's very scary, this group of people that claim to be these peaceful prayer warriors, or whatever they call themselves, it's kind of ironic that some of them would be sending death threats." The Planned Parenthood clinic named Johnson employee of the year in 2008.
Johnson says that in September 2009, she was called in to assist in an ultrasound-guided abortion at 13 weeks gestation. She said she was disconcerted to see how similar the ultrasound image looked to her own daughter's. Johnson, who previously believed fetuses could not feel anything while being aborted, says she saw the fetus squirming and twisting to avoid the vacuum tube used for the abortion.
"For the briefest moment," she wrote in her memoir, Unplanned, "the baby looked as if it were being wrung like a dishcloth, twirled and squeezed. And then it crumpled and began disappearing into the cannula before my eyes. The last thing I saw was the tiny, perfectly formed backbone sucked into the tube, and then it was gone."
Johnson continued working at the clinic for 9 more days, but soon met with Shawn Carney, leader of the local anti-abortion group Coalition for Life, with whom she was well-acquainted after his years of activism against Planned Parenthood. She told him she could no longer continue assisting women in getting abortions. She resigned on October 6, 2009.
Johnson said after her resignation that her bosses had pressured her to increase profits by performing more and more abortions at the clinic. Johnson estimated the clinic profited $350 on every abortion.
An article on Salon.com questioned Johnson's statements regarding financial incentives for abortions, noting that abortions comprise only 3% of Planned Parenthood's services. Fox News reported that Johnson was unable to provide any documentation or other evidence to support her allegations about pressure to perform abortions.
Johnson's description of her conversion has been questioned. Planned Parenthood stated that its records do not show any ultrasound-guided abortions performed on the date Johnson says she witnessed the procedure, and the physician who performed abortions at the Bryan clinic stated that Johnson had never been asked to assist in an abortion. Although Johnson said the abortion was of a 13-week-old fetus, records from the Texas Department of Health show no such abortions performed at the Bryan clinic on the date in question.
According to a court petition filed by Planned Parenthood, Johnson was put on a "performance improvement plan" four days before her resignation. The petition says that following this she was seen "removing items" from the clinic and copying "confidential files" and had given the résumé, home address, and phone number of an abortion provider to Coalition for Life. Planned Parenthood was granted a temporary restraining order against Johnson and Coalition for Life after Johnson's resignation. The order was lifted by a court a week later. Johnson herself says the "performance improvement plan" was due to her reluctance to increase the number of abortions performed at her facility. Johnson also denies the accusations that she removed, copied, or distributed any confidential information and said in her book that her attorney disproved them at the time that the temporary restraining order was lifted.
Johnson's story received national coverage. She was embraced by the anti-abortion movement after her story went national in November 2009 and compared to Norma McCorvey, the "Jane Roe" of Roe v. Wade, the United States Supreme Court case that legalized abortion in 1973. McCorvey joined the pro-life movement in 1995.
Soon after her resignation, Johnson began volunteering with the Coalition for Life, which regularly prayed outside her former clinic.
Johnson has since adopted the consistent life ethic, opposing not just abortion—in all cases—but also the death penalty and euthanasia. She affirms natural family planning over the use of any form of birth control.
Johnson is the author of two books. Unplanned (ISBN 1414339399), released in January 2011, details her work at Planned Parenthood and her conversion to the anti-abortion cause. The Walls Are Talking: Former Abortion Clinic Workers Tell Their Stories (ISBN 1586177974), released in 2016, recounts stories of former abortion workers that have come through her ministry.
Johnson now runs an anti-abortion ministry, And Then There Were None (ATTWN). The organization seeks to help abortion clinic workers leave the industry. ATTWN was founded in 2012.
Johnson planned to attend the 2017 Women's March in Washington D.C. on January 21, 2017. She was one of the speakers at the 2017 March for Life rally, an annual rally protesting abortion and Roe v. Wade.
Johnson revealed in January 2011 that she had had two abortions herself before the birth of her daughter. She lives in Texas with her husband Doug and children.
Johnson was raised as a Southern Baptist, but left the church because it objected to her work at Planned Parenthood. She and her husband Doug, who was raised Lutheran, stopped attending church altogether for two years before joining the Episcopal Church, which has one of the most liberal stances on abortion of any Mainline Protestant denomination. After she went public with her conversion to the anti-abortion position, Johnson said she felt unwelcome at this church. She converted to Catholicism in 2012.