Congresswoman Barbara Lee was born in segregated El Paso, TX and attended St. Joseph's Catholic School, where she was taught by the Sisters of Loretto, an order dedicated to promoting justice and peace. Her father was a veteran of two wars and her mother broke many glass ceilings and racial barriers. After grammar school, Congresswoman Lee moved to San Fernando, California and worked with the local NAACP to integrate her high school cheerleading squad.

As a single mother raising two sons, Congresswoman Lee attended Mills College and received public assistance while building a better life for her family. As president of Mills College's Black Student Union, she invited Congresswoman Shirley Chisholm, the first African American woman elected to Congress, to speak on campus. Congresswoman Lee received her Masters of Social Work from the University of California, Berkeley, specializing in psychiatric social work. During her graduate work, Congresswoman Lee founded the Community Health Alliance for Neighborhood Growth and Education (CHANGE, Inc.) which provided mental health services to many of the East Bay's most vulnerable individuals.

In 1975, Congresswoman Lee joined the staff of Congressman Ron Dellums, where she eventually rose from an intern to chief of staff. During the eleven years she worked for Congressman Dellums, Congresswoman Lee was one of only a few women and persons of color to hold a senior position on Capitol Hill.

In 1990, Congresswoman Lee was elected to the California State Assembly, where she served until 1996 when she was elected to the State Senate. As a California legislator, Congresswoman Lee authored 67 bills and resolutions that were signed into law by Republican Governor Pete Wilson. This legislation addressed a wide spectrum of issues, including public safety, education, healthcare, and environmental protections. In the legislature, Congresswoman Lee was an early champion of LGBT issues and authored the 1995 California Schools Hate Crimes Reduction Act. As the first African American woman elected to the State Senate from Northern California, Congresswoman Lee created and presided over the California Commission on the Status of African American Males and the California Legislative Black Caucus, while working to defeat the punitive "three strikes law." Congresswoman Lee also served as a strong advocate for women in the legislature, where she authored and passed the first California Violence Against Women Act and served as a member of the California In 1998, Congresswoman Barbara Lee was elected to serve California's 9th congressional district (now the 12th) in a special election.

In 2001, Congresswoman Lee received national attention as the only Member of Congress to oppose the authorization for the use of military force (AUMF) in the wake of the horrific events on September 11th. The Congresswoman believed this AUMF would become a blank check for endless war. As of 2013, this authorization had been used more than 30 times to engage in military action without Congressional oversight. Congresswoman Lee is working to repeal this blank check and restore Congress's constitutional oversight to matters of war and peace. She was also an outspoken opponent of the Iraq War.

Congresswoman Lee has long advocated for legislative action to end poverty. In 2007, she worked with a diverse coalition of Members to create the Out of Poverty Caucus. In 2013, she became chair of the Democratic Whip Task Force on Poverty and Opportunity. As chair, she leads more than 100 Members of Congress in crafting and advancing legislation to lift millions of American families out of poverty and into the middle class.

Since her time in the California legislature, Congresswoman Lee has been a fierce advocate for ending HIV and ensuring an AIDS-free generation. Since entering Congress, she has authored or co-authored every major piece of HIV/AIDS legislation including the legislative frameworks for the President's Emergency Plan for AIDS Relief (PEPFAR) and the Global Fund to Fight AIDS, Tuberculosis and Malaria. Congresswoman Lee's legislation establishing a USAID special advisor for orphans and vulnerable children was enacted into law in 2009. In 2011, Congresswoman Lee formed the bipartisan and bicameral Congressional HIV/AIDS Caucus, which she co-chairs.

Currently, Congresswoman Lee serves on the Budget Committee and the powerful Appropriations Committee, which oversees all federal government spending. She serves on three subcommittees (Ranking Member, State and Foreign Operations; Labor, Health and Human Services, Education; and Agriculture, Rural Development, Food and Drug Administration) of the Appropriations Committee. In January 2021, she became the first African-American to chair the House Appropriations Subcommittee on State, Foreign Operations, and Related Programs.

Congresswoman Lee is the highest ranking African American woman appointed to Democratic Leadership, serving as Co-Chair of the Policy and Steering Committee. As Co-Chair, Rep. Lee works to ensure that committees reflect the diversity, dynamism, and integrity of the Democratic Caucus. She also works to advance the policies that comprise the Democratic "For the People" agenda. In addition, she currently serves as the Chair of the Majority Leader's Task Force on Poverty and Opportunity, Co-Chair of the Pro-Choice Caucus, and Co-Chair of the Cannabis Caucus. She is the former chair of the Congressional Black Caucus (111th Congress) and co-chair of the Congressional Progressive Caucus (109th & 110th Congresses).