Michele Marie Amble was born in Waterloo, Iowa on April 6, 1956, to Norwegian-American parents David John Amble (1929–2003) and "Arlene" Jean Amble (née Johnson) (born c. 1932). One pair of her great-great-great grandparents, Melchior and Martha Munson, left Sogndal in Norway and arrived in Wisconsin in 1857. She was still a young girl when her father, an Engineer, moved the family to Brooklyn Park, Minnesota. She was 14 years old when her parents filed for divorce. Her father remarried and moved to California, and young Michele and her mother Jean moved to Anoka, Minnesota. Her mother remarried three years later to widower Raymond J. LaFave.

Bachmann said: "... the immigration system in the United States worked very, very well up until the mid-1960s when liberal members of Congress changed the immigration laws."

Bachmann grew up in a Democratic family, but she says she became a Republican during her senior year at Winona State. She told the Minneapolis Star Tribune that she was reading Gore Vidal's 1973 novel Burr: "He was kind of mocking the Founding Fathers and I just thought, I just remember reading the book, putting it in my lap, looking out the window and thinking, 'You know what? I don't think I am a Democrat. I must be a Republican.'"

She graduated from Anoka High School in 1974 and, after graduation, spent one summer working on kibbutz Be'eri in Israel. In 1978, she graduated from Winona State University with a B.A.

While still a Democrat, she and her then-fiancé Marcus were inspired to join the pro-life movement by Francis Schaeffer's 1976 Christian documentary film How Should We Then Live? They prayed outside of clinics and engaged in sidewalk counseling, a pro-life protest activity in which Activists approach people entering abortion clinics in an attempt to dissuade women from obtaining abortions. Since then, Bachmann has made statements supportive of sidewalk counseling. Bachmann was a supporter of Jimmy Carter in 1976, and she and her husband worked on his campaign. During Carter's presidency, Bachmann became disappointed with his liberal approach to public policy, support for legalized abortion and economic decisions she held responsible for increased gas prices. In the 1980 presidential election, she voted for Ronald Reagan and worked for his campaign.

In 1978, she married Marcus Bachmann, now a clinical therapist with a master's degree from Regent University and a Ph.D. from Union Graduate School, whom she met while they were undergraduates. After she received an LL.M. in taxation from william & Mary School of Law in 1988, the couple moved to Stillwater, Minnesota, a town of 18,000 near Saint Paul, where they run a Christian counseling center that provided gay conversion therapy. Bachmann and her husband have five children: Lucas, Harrison, Elisa, Caroline, and Sophia. Bachmann said in a 2011 town hall meeting that she suffered a miscarriage after the birth of their second child, Harrison, an event she said shaped her pro-life views.

In 1979, Bachmann was a member of the first class of the O. W. Coburn School of Law, then a part of Oral Roberts University (ORU). While there, Bachmann studied with John Eidsmoe, whom she described in 2011 as "one of the professors who had a great influence on me". Bachmann worked as a research assistant on Eidsmoe's 1987 book Christianity and the Constitution, which argues that the United States was founded as a Christian theocracy and should become one again. In 1986 Bachmann received a J.D. degree from Oral Roberts University. She was a member of the ORU law school's final graduating class, and was part of a group of faculty, staff, and students who moved the ORU law school library to what is now Regent University.

In 1988, Bachmann received an LL.M. degree in tax law from william & Mary Law School. From 1988 to 1993 she worked as an attorney for the Internal Revenue Service (IRS). She left the IRS to become a full-time mother when her fourth child was born.

Her political activism gained media attention at a pro-life protest in 1991. She and approximately 30 other pro-life citizens went to a Ramsey County Board meeting where a $3 million appropriation was to go to build a Morgue for the county at St. Paul-Ramsey Medical Center (now Regions Hospital). The Medical Center performed abortions and employed pro-choice Activist Jane Hodgson. Bachmann attended the meeting to protest public tax dollars going to the hospital; speaking to the Star Tribune, she said that "in effect, since 1973, I have been a landlord of an abortion clinic, and I don't like that distinction".

Bachmann and her husband have also provided foster care to 23 other children, all teenage girls. The Bachmanns were licensed from 1992 to 2000 to handle up to three foster children at a time; the last child arrived in 1998. The Bachmanns began by providing short-term care for girls with eating disorders who were patients in a University of Minnesota program. The Bachmann home was legally defined as a treatment home, with a daily reimbursement rate per child from the state. Some girls stayed a few months, others more than a year.

In 1993, she and other parents started the K-12 New Heights Charter School in Stillwater. The publicly funded school's charter mandated that it be non-sectarian in all programs and practices, but the school soon developed a strong Christian orientation. Parents of students at the school complained and the superintendent of schools warned Bachmann that the school was in violation of state law. Six months after the school's founding Bachmann resigned and the Christian orientation was removed from the curriculum, allowing the school to keep its charter. Bachmann began speaking against a state-mandated set of educational standards, which propelled her into the world of politics.

In November 1999, she and four other Republicans were candidates, as the "Slate of Five", in an election for the school board of Stillwater. All five lost.

In 2000, Bachmann defeated 18-year incumbent Gary Laidig for the Republican nomination for State Senator for Minnesota District 56. In the November 2000 general election, she defeated Ted Thompson of the Minnesota Democratic-Farmer-Labor Party (DFL) and Lyno Sullivan of the Minnesota Independence Party, to win the seat. Two years later, in November 2002, after redistricting due to the 2000 Census, Bachmann defeated another incumbent, State Senator Jane Krentz of the DFL, in the newly drawn State Senate District 52. In office, Bachmann's agenda focused on the cultural conservative issues of opposition to abortion and gay marriage.

The U.S. 6th District's congressman since 2001, Mark Kennedy, announced in late 2005 that he would be running for the U.S. Senate seat being vacated by Mark Dayton of the DFL. Bachmann states "God then called me to run" for the U.S. House seat, and that she and her husband fasted for three days to be more sure.

According to an article in the Stillwater Gazette, a local newspaper in Minnesota, Bachmann supports the teaching of creationism alongside evolution in public school science classes. During a 2003 interview on the KKMS Christian radio program Talk The Walk, Bachmann said that evolution is a theory that has never been proven one way or the other. She co-authored a bill (that received no additional endorsement among her fellow legislators) that would require public schools to include alternative explanations for the origin of life as part of the state's public school science curricula. In October 2006, Bachmann told a debate audience in St. Cloud, Minnesota "there is a controversy among Scientists about whether evolution is a fact or not ... There are hundreds and hundreds of Scientists, many of them holding Nobel Prizes, who believe in intelligent design." However, at least one news report, presenting a "sampling of Bachmann's ... ludicrous or plain old false claims", stated that this was untrue, and that "when the science isn't on [Bachmann's] side, she simply improvises."

In November 2004, Republican Senate Minority Leader Dick Day appointed Bachmann as Assistant Minority Leader in charge of Policy for the Senate Republican Caucus. In July 2005, the Republican Caucus removed her from her leadership position. Bachmann said that disagreements with Day over her anti-tax stance were the reason for her ouster.

In 2005, Bachmann opposed Minnesota Governor Tim Pawlenty's proposal for a state surcharge of 75 cents per pack on the wholesale cost of cigarettes. Bachmann said that she opposed the state surcharge "100 percent—it's a tax increase." She later was criticized by the Taxpayers' League for reversing her position and voting in favor of the cigarette surcharge.

Bachmann received support from a fundraising visit in early July 2006 from Speaker of the House Dennis Hastert. On July 21, 2006, Karl Rove visited Minnesota to raise funds for her election. In August, President George W. Bush was the keynote speaker at her congressional fundraiser, which raised about $500,000. Bachmann also received fundraising support from Vice President Dick Cheney. The National Republican Congressional Committee put nearly $3 million into the race, for electronic and direct-mail ads against DFLer Wetterling. The amount was significantly more than the Democratic Congressional Campaign Committee spent on behalf of Wetterling. On November 7, 2006, Bachmann defeated opponents Patty Wetterling and John Binkowski, taking 50 percent of the vote to Wetterling's 42 percent and Binkowski's eight percent.

On July 11, 2007, Bachmann voted against the College Cost Reduction and Access Act that raised the maximum Pell grant from $4,310 to $5,200, lower interest rates on subsidized student loans to 3.4 percent from 6.8 percent, raise loan limits to $30,500 from $7,500, disfavor married students who file joint tax returns, provide more favorable repayment terms to students who fail to use their education to prosper financially and favor public sector over private sector workers with much more favorable loan forgiveness benefits. Supporters of the bill said "it would allow more students to attend college". Bachmann said her opposition was because "it fails students and taxpayers with gimmicks, hidden costs and poorly targeted aid. It contains no serious reform of existing programs, and it favors the costly, government-run direct lending program over nonprofit and commercial lenders." The bill passed the House and was signed by President Bush.

In 2008, Bachmann won re-election over her DFL and Independence Party endorsed opponent Elwyn Tinklenberg. With all precincts reported, Bachmann won, 46.41% to 43.43%. Because Tinklenberg was running as a DFLer in the Democratic primary this allowed candidate Bob Anderson to run in the Independence Party primary unopposed despite not having the Independence endorsement. Anderson received 10% of the vote.

On August 31, 2009, Bachmann spoke at an event in Colorado, saying of Democratic health care overhaul proposals that:

Bachmann was challenged in 2010 by DFL nominee Tarryl Clark and Independence Party candidate Bob Anderson. With more than $8.5 million, Bachmann spent more than any other House of Representative candidate, although her opponent, Tarryl Clark, was able to raise $4 million, one of the largest fundraising efforts in the nation for a U.S. House challenger. On November 2, 2010, Bachmann defeated Tarryl Clark by 52% to 40% of the vote.

In November 2011 Bachmann published her autobiography, Core of Conviction, in which she outlines the events and people who have shaped her values and beliefs including her parents' divorce when she was in the ninth grade. She describes the financial struggles her mother suffered as a single parent in trying to provide for her family and the work ethic she developed as a result of it. She writes of that time, "I took every baby sitting job I could get, because by ninth grade, I was growing conscious of my appearance. In those days, girls had to wear dresses to public school, and if I wanted pretty dresses, I had to buy them, because mom couldn't afford them for me; she couldn't afford lunch money."

According to Politico.com, as of July 2012, Bachmann has "raised close to $15 million" for the 2012 election, a figure it called "astounding ... more than some Senate candidates will collect this year." From July to the end of September, Bachmann raised $4.5 million. This amount put her ahead of all other members of congress (including Allen West who was in second place with $4 million) for the third quarter. Bachmann said that she was "humbled by the enormous outpouring of grassroots support for my campaign focused on keeping America the most secure and prosperous nation in the world."

She is against the 2013 immigration reform bill, indicating that passing it would mean the end of the Republican Party. On WorldNetDaily she stated "This is President Obama's number one political agenda because he knows we will never again have a Republican President ever if amnesty goes into effect."

Additionally, a lawsuit was filed alleging that Bachmann and several former staffers stole and misused an Iowa homeschool group's e-mail distribution list. The trial, Heki v. Bachmann, had been set for May 14, 2014, but the case was settled out of court on June 28, 2013.