Throughout 2007 and 2008, she helped campaign for her husband's presidential bid and delivered a keynote address at the 2008 Democratic National Convention. She is the mother of two daughters, Malia and Sasha, and is the sister of Craig Robinson, men's basketball coach at Oregon State University. As the wife of a Senator, and later the First Lady, she has become a fashion icon and role model for women, and a notable advocate for poverty awareness and healthy eating.

Michelle LaVaughn Robinson was born on January 17, 1964, in Chicago, Illinois to Fraser Robinson III, a city water plant employee and Democratic precinct captain, and Marian Shields Robinson, a secretary at Spiegel's catalog store. Her mother was a full-time homemaker until Michelle entered high school. The Robinson and Shields families can trace their roots to pre-Civil War African Americans in the American South. Her paternal great-great grandfather, Jim Robinson, was an American slave in the state of South Carolina, where some of her paternal family still reside. Her maternal great-great-great grandmother, Melvinia Shields, also a slave, became pregnant by a white man. His name and the nature of their union have been lost. She gave birth to Michelle's biracial maternal great-great grandfather, Dolphus T. Shields.

She grew up in a two-story house on Euclid Street in Chicago's South Shore community area. Her parents rented a small apartment on the house's second floor from her great-aunt, who lived downstairs. She was raised in what she describes as a "conventional" home, with "the mother at home, the father works, you have dinner around the table". The family entertained together by playing games such as Monopoly and by reading. The family attended services at nearby South Shore Methodist Church. The Robinsons used to vacation in a rustic cabin in White Cloud, Michigan. She and her brother, Craig (who is 21 months older), skipped the second grade. By sixth grade, Michelle joined a gifted class at Bryn Mawr Elementary School (later renamed Bouchet Academy).

She attended Whitney Young High School, Chicago's first magnet high school, where she was on the honor roll for four years, took advanced placement classes, was a member of the National Honor Society and served as student council treasurer. The round trip commute from her South Side home to the Near West Side took three hours. She was a high school classmate of Santita Jackson, the daughter of Jesse Jackson and sister of Jesse Jackson, Jr. She graduated from high school in 1981 as salutatorian.

Michelle was inspired to follow her brother to Princeton University; he graduated in 1983. At Princeton, she challenged the teaching methodology for French because she felt that it should be more conversational. As part of her requirements for graduation, she wrote a thesis entitled, "Princeton-Educated Blacks and the Black Community." "I remember being shocked," she says, "by college students who drove BMWs. I didn't even know parents who drove BMWs." While at Princeton, she got involved with the Third World Center (now known as the Carl A. Fields Center), an academic and cultural group that supported minority students, running their day care center which also included after school tutoring. Robinson majored in sociology and minored in African American studies and graduated cum laude with a Bachelor of Arts in 1985. She earned her Juris Doctor (J.D.) degree from Harvard Law School in 1988. At Harvard she participated in demonstrations advocating the hiring of professors who were members of minorities and worked for the Harvard Legal Aid Bureau, assisting low-income tenants with housing cases. She is the third First Lady with a postgraduate degree, following Hillary Rodham Clinton and Laura Bush. In July 2008, Obama accepted the invitation to become an honorary member of the 100-year-old black sorority Alpha Kappa Alpha, which had no active undergraduate chapter at Princeton when she attended.

She met Barack Obama when they were among the few African Americans at their law firm, Sidley Austin (she has sometimes said only two, although others have pointed out there were others in different departments), and she was assigned to mentor him as a summer associate. Their relationship started with a business lunch and then a community organization meeting where he first impressed her. The couple's first date was to the Spike Lee movie Do the Right Thing. The couple married in October 1992, and they have two daughters, Malia Ann (born 1998) and Natasha (known as Sasha, born 2001). After his election to the U.S. Senate, the Obama family continued to live on Chicago's South Side, choosing to remain there rather than moving to Washington, D.C. Throughout her husband's 2008 campaign for President of the United States, she made a "commitment to be away overnight only once a week — to campaign only two days a week and be home by the end of the second day" for their two children. She is the sister of Craig Robinson, men's basketball coach at Oregon State University. She is the first cousin, once removed, of Rabbi Capers C. Funnye Jr., one of the country’s most prominent black rabbis.

She once requested that her then-fiancé meet her prospective boss, Valerie Jarrett, when considering her first career move. Now Jarrett is one of her husband’s closest advisors. The marital relationship has had its ebbs and flows; the combination of an evolving family life and beginning political career led to many arguments about balancing work and family. Barack Obama wrote in his second book, The Audacity of Hope: Thoughts on Reclaiming the American Dream, that "Tired and stressed, we had little time for conversation, much less romance". However, despite their family obligations and careers, they continue to attempt to schedule date nights.

The Obamas' daughters attended the University of Chicago Laboratory Schools, a private school. As a member of the school's board, Michelle fought to maintain diversity in the school when other board members connected with the University of Chicago tried to reserve more slots for children of the university faculty. This resulted in a plan to expand the school. The Obamas' daughters now attend Sidwell Friends School in Washington, after also considering Georgetown Day School. She stated in an interview on the The Ellen DeGeneres Show that the couple does not intend to have any more children. They have received advice from past first ladies Laura Bush, Rosalynn Carter and Hillary Rodham Clinton about raising children in the White House. Marian Robinson, Michelle's mother, has moved into the White House to assist with child care.

Following law school, she was an associate at the Chicago office of the law firm Sidley Austin, where she first met her future husband. At the firm, she worked on marketing and intellectual property.

In 1991, she held public sector positions in the Chicago city government as an Assistant to the Mayor, and as Assistant Commissioner of Planning and Development. In 1993, she became Executive Director for the Chicago office of Public Allies, a non-profit organization encouraging young people to work on social issues in nonprofit groups and government agencies. She worked there nearly four years and set fundraising records for the organization that still stood 12 years after she left.