Initially, Lani was educated at Andrew Jackson High School. She continued her studies and attained Bachelor of Arts degree, graduating from Radcliffe College in 1971. Three years later, in 1974, Guinier got her Juris Doctor degree at Yale University Law School.
In 1992 she obtained honorary degree from University of Pennsylvania.
Lani started her career as a law clerk in 1974 for Judge Damon Keith of the United States Court of Appeals for the Sixth Circuit and held the post till 1976, when she became a juvenile court referee at Wayne County Juvenile Court in Detroit, Michigan. Lani held the post until 1977. The same year she was appointed a special assistant to General Drew S. Days, at Civil Rights Division, United States Department of Justice.
In 1981 Guinier started to serve as an assistant council at National Association for the Advancement of Colored People (NAACP) Legal Defense and Educational Fund, a position she held till 1988.
Beginning from 1985 to 1989 Lani served as an adjunct professor at New York University School of Law. Also, in 1988 she was appointed a professor of law at University of Pennsylvania Law School in Philadelphia, Pennsylvania, United States and served there for ten years, before joining Harvard Law School in 1998.
On April 29, 1993 Lani Guinier was nominated by President Bill Clinton for the post of an assistant attorney general at Civil Rights Division, United States Department of Justice. But Guinier came under attack by conservative politicians for her writings on racial justice that had been published in law journals and were later collected in The Tyranny of the Majority: Fundamental Fairness in Representative Democracy and on June 3, 1993 the nomination was withdrawn.
In 2007 Guinier worked as a visiting professor at Columbia Law School.
Currently, she lectures at various law schools and universities, such as Yale University, Stanford University, New York University, University of Chicago and others.
In her scholarly writings and in op-ed pieces, Lani Guinier has addressed issues of race, gender and democratic decision-making, and sought new ways of approaching questions like affirmative action while calling for candid public discourse on these topics.
"In a racially divided society, majority rule is not a reliable instrument of democracy."
"As a country, we are in a state of denial about issues of race and racism. And too many of our leaders have concluded that the way to remedy racism is to simply stop talking about race."
Lani married Nolan A. Bowie in 1986. The couple has a child, Niklas.