Janice grew up at The Culver City Housing Projects in Los Angeles, until age 11. Her parents, Felice and Harvey Karman, studied theatre and film at UCLA - where her father would bring home the cameras for the weekend to make movies with help from the kids in their row in the project. Due to her family being poor, her father always made sure they had season tickets to the music centre, where she saw movies such as Man of La Mancha, Oliver, Fiddler on the Roof, My Fair Lady, all the classics.
When she was 16, she raised enough money to send herself to Europe for four months; visiting London, Paris and Amsterdam by herself. Being close with her family, she did this to see how she would respond without them to rely on. In her family, they were encouraged to challenge their fears.
Janice took theatre, film and directing classes at UCLA Extension. She received a scholarship at the Strasberg Institute. She was terribly shy and self-conscious in front of people and thought acting would help, but she wasn't someone who blossomed on stage, however, as she quotes "It was like pushing an elephant up the stairs."
She met Ross when she was 19 years old, and admitted that he had stalked her for years, for he knew they were meant for one another. She mentioned that one day he came over to her boyfriend's house, where she asked him to stop and that he was making her life miserable, before looking him in the eyes and saying she doesn't love him after he had asked her to "Look me in the eye and tell me you don't love me, and I will leave you alone". Ross continued to persue her and saying that he didn't believe her. And then one day she fell madly, head-over-heels in love.
- Janice once made a preschool show for kids about emotional intelligence, which dealt with different issues: jealousy, lying, sibling rivalry. She'd put it out for a short while to get some reactions, which turned out to all be positive.
- Janice's favourite books are The Pillars of The Earth by Ken Follet, Prince of Tides by Pat Conroy, The Joy Luck Club by Amy Tan, and The Other Boleyn Girl.
- Janice is a vegetarian.
- She directed The Chipmunk Adventure as well as providing the voices for Theodore, Brittany, Jeanette, and Eleanor.
- In the Alvin and the Chipmunks, The Chipmunks, and The Chipmunks Go to the Movies television series, Karman provides the speaking and singing voices for Theodore, Brittany, Jeanette, and Eleanor. She was also the co-creator of The Chipettes.
- In Alvin and the Chipmunks, Karman provides the singing voice for Theodore. For promotional reasons, she lost her speaking role to Jesse McCartney.
- In Alvin and the Chipmunks: The Squeakquel, Karman provides the singing voices of Theodore and the Chipettes. However, like Theodore, she does not provide the speaking voices for The Chipettes like she did in the cartoons. Instead, the Chipettes are now voiced by Christina Applegate (Brittany), Anna Faris (Jeanette), and Amy Poehler (Eleanor).
- She retains her singing roles for Alvin and the Chipmunks: Chipwrecked.
- She makes an appearance as herself in Michael Bagdasarian's 2008 short video, Are Freshmen Getting Smaller?