Andrea Lewis was born and raised in Detroit and earned her bachelor's degree from Eastern Michigan University. She moved to the Bay Area in 1983 and began her career in journalism as a calendar, arts & entertainment editor for Plexus: West Coast Women's Press. In 1988, she began working for Mother Jones magazine, and within a few months was hired as a research editor. She became an editorial assistant in 1991 for HarperSanFrancisco, a division of HarperCollins Publishers. In 1993, Lewis became a senior editor for Third Force magazine (now Color Lines), after working with the publication as a freelance editor for many years. She joined the staff of Pacific News Service in San Francisco (now New America Media) in 1996 as an associate editor and an editor for YO! (Youth Outlook). In December 1999, she was hired as the co-host and producer of "The Morning Show" at KPFA Radio in Berkeley, the first listener-sponsored radio station in the country. In addition to her work in radio, she contributes to several other news outlets, including the Progressive Media Project, which seeks to increase the diversity of representation on the op-ed pages of daily newspapers. She was the recipient of a National Federation of Community Broadcasters Golden Reels Award in 2002 and a John Swett Award for Media Excellence 2004 from the California Teachers Association. She was a fellow in the Society of Professional Journalists Diversity Leadership Program from 2006-2007.

Andrea Lewis is a member of the Stanford University John S. Knight Journalism Fellowship Class of 2008. During her time at Stanford, Lewis' focus of study was "the role of alternative journalism in contemporary American culture and democracy." In July of 2007, Lewis returned to the airwaves of KPFA as a co anchor of The Evening News and the host and producer of KPFA's Sunday morning public affairs program.