Scarwid has more than 70 film and television credits, including Pretty Baby (1978), Rumble Fish (1983), Silkwood (1983), Psycho III (1986), Extremities (1986), The Neon Bible (1995), What Lies Beneath (2000), Party Monster (2003), The Clearing (2004), and Another Happy Day (2011).
She graduated from The American Academy of Dramatic Arts and Pace University simultaneously, completing the dual program as an honor student.
In television movies, Scarwid had performances in Desperate Lives (1982), Strange Invaders, Rumble Fish (1983), Silkwood (1983), The Ladies Club, Psycho III (1986), Extremities (1986), and After the Promise (1987).
In 1996, Scarwid had roles in Trial By Fire and Bastard Out of Carolina, If These Walls Could Talk, Critical Choices, The Angel of Pennsylvania Avenue and The Outer Limits.
The same year, she guest-starred as Jeanette Owens in Prison Break, following which she assumed the role of Isabel, a mysterious sheriff and island inhabitant in the TV series Lost.