McNamara moved from Baltimore to Westminster in elementary school. She graduated from Westminster Senior High School and attended the University of Missouri School of Journalism. While at Missouri, she reported for the Columbia Missourian. Upon her graduation, McNamara wrote for Ms. Magazine, then worked for Whittle Communications. McNamara joined the Los Angeles Times in 1991 as a features writer and editor. In 2009, she became the Times' television critic.
- Barnes, Henry (April 21, 2015). "Three female critics nominated for Pulitzer prize". The Guardian. Retrieved April 27, 2015.
- Lake, Brett (June 10, 2013). "Q&A: Westminster native reflects on being named Pulitzer Prize finalist". Carroll County Times. Retrieved April 27, 2015.
- Rees, Annie (June 15, 2015). "Alumna Mary McNamara Earns Pulitzer Prize in the Criticism Category". University of Missouri School of Journalism. Retrieved August 13, 2015.