Lawson was born in Los Angeles, California. She started acting at the age of nine when she appeared in commercials for Barbie.
In 1993, Lawson was one of the original cast members of Saved by the Bell: The New Class, she also appeared in multiple episodes of The WB sitcoms Sister, Sister, The Parent 'Hood and The Steve Harvey Show.
Most recently Lawson played Maya St. Germain in the ABC Family series Pretty Little Liars based on the book series by Sara Shepard.
She is perhaps best remembered by genre fans for her stint on Buffy the Vampire Slayer. Lawson portrayed Kendra Young, another Vampire Slayer who is activated as a result of Buffy's temporary death.
She later portrayed the witch, Emily Bennett, in another vampire-related series, The Vampire Diaries.
She also had a memorable role on Dawson's Creek playing Nikki Green, principal's daughter and Dawson love interest.
Some of Lawson's film credits include Primary Colors (1998), Save the Last Dance (2001), Bones (2001) and Breakin' All the Rules (2004).