Flint started her writing career with television series China Beach (1988-1991). After that series ended, she started working on the television series L.A. Law in 1986, writing the episodes "The Nut Before Christmas," "From Here to Paternity" and "Love in Bloom".
In 1994, she started working on the NBC drama ER, which she also co-produced. She wrote and executive produced the series Earth 2 (1994-1995). In 1999, she began work on The West Wing, and wrote five episodes for the series. More recently, she was a writer and co-producer of the series The Court, of which six episodes were produced but only three aired. In 2006, Flint co-produced the television series The Unit and Six Degrees. Flint recently completed a feature script for Warner Bros., entitled How It Was with Dooms. Since 2009, she has been either consulting producer or co-executive producer for Royal Pains on USA Network, for which she also has authored several episodes.