Jennie began acting at the age of eleven, when she started performing with the touring company, "Kids of the Century". Her first television role was in 1991 as the voice of Audrey in Little Shop, a series based on the 1986 film Little Shop of Horrors.
Jennie is most notable for portraying the character Samantha Woo on NBC's hit show, California Dreams. In 1992, she auditioned for the lead role as Tiffani, but lost out to Kelly Packard. However, the incident led to them being best friends until this day. In that same year, she also appeared in an episode of Beverly Hills, 90210. In January 1993, she began performing the role as Kim in Chicago's production of Miss Saigon. Later that year, the producers of California Dreams called her back to join the main cast, playing the role of Sam, a foreign exchange student. Kwan replaced Heidi Noelle Lenhart, who, coincidentally, played the role of Jenny, in the main cast and remained with the show until its cancellation in 1997.
She starred in the Las Vegas original cast of the musical Avenue Q, and spent time starring in the national tour as an understudy for the role of Christmas Eve. In late 2008, Jennie was let go from the cast and released from her contract. Her bio was quickly taken off the show's site. No press release was issued announcing whether or not it was her decision to leave.
In 2009, she provided the voice for Bitgirl, Myang Myang and Edu in Random! Cartoons.