Dawson's first professional acting job was in a Broadway production of A Chorus Line. She continued a stage career through the 1980s and 1990s, while occasionally landing minor film and television roles.
Dawson's first play, Desire to Fall, was produced by the Circle Repertory Company workshop in 1986. Dawson's second play, Passage Through the Heart, debuted in 1997 at the University of Minnesota Duluth.
After her divorce in 1987 from actor Casey Biggs, who himself later became a fellow Star Trek cast member (portraying the Cardassian Damar in Deep Space Nine), Roxann married casting Director Eric Dawson in May 1994. They had first met in 1989 when she was in the cast of the NBC television drama Nightingales. They have two daughters: Emma (b. 1998) and Mia (b. 1999).
In 1994, Dawson began her role as the half Human/half-Klingon Engineer B'Elanna Torres on Star Trek: Voyager, which lasted for all seven seasons of the show. While working on Voyager, Dawson made her directorial debut on the episode "Riddles", which aired in September 1999. She later directed the second part of the two-part episode "Workforce" and directed 10 episodes of Star Trek: Enterprise. In 2002 she provided the voice of the Repair Station Computer in "Dead Stop", one of the Star Trek: Enterprise episodes she directed.
From 2000 to 2001, Dawson co-wrote, with Daniel Graham, a trilogy of science-fiction novels, Entering Tenebrea (ISBN 0-671-03607-6), Tenebrea's Hope (ISBN 0-671-03609-2) and Tenebrea Rising (ISBN 0-671-03611-4).
In 2004 she bought a house in Bell Canyon, California.
She has directed episodes of Charmed, The O.C., Close to Home (where she directed fellow Star Trek alum Connor Trinneer), Lost, Heroes, Hawthorne, The Closer, Cold Case, Caprica (produced by Star Trek veteran Ronald D. Moore), The Mentalist and Treme. In 2010, she directed "Teacher and Pupils", a second-season episode of Lie to Me and "On Tap", a second-season episode of The Good Wife. In 2013, she directed "Reunions", the March 22 episode of Touch, and "Eye-Spy", the October 15 episode of Agents of S.H.I.E.L.D..
In 2014 she directed "Dreamcatcher", the March 5 episode of Revolution and "Phobia", the October 22 episode of Stalker. For the 2015 season of the Amazon Original Series Bosch, she directed episode 6, "Chapter Six: Donkey's Years". She directed early episodes of Mercy Street, a series released on PBS in January 2016. In 2016, she also directed the episodes "Broussard" and "Zero Day" for season 1 of the TV series Colony. She's also directed the episode "Crossbreed" of The Americans (season 5). She also directed episode 8 of the fifth season of House of Cards, "Chapter 60".
