Born in Seoul, South Korea, Jennifer Whalen began her training at the age of seven under Linda Strangio-Hedberg in Ventura, California. She was a founding member of Young Dancers Ensemble in Ventura and a founding member of the State Street Ballet Young Dancers in Santa Barbara. Whalen has also trained on scholarship with the San Francisco Ballet, The Kirov Academy and The Royal Ballet School.
She made her professional debut in 1999, at the age of 14, with the State Street Ballet when the role of Clara in their Hollywood Nutcracker was created on her. While at State Street Ballet, Whalen also danced the role of The Bird in Robert Sund's Beauty and the Beast and the role of Tiger Lily in Sund's Alice in Wonderland. She also danced the solo Yu: Gift of Heaven choreographed for her by Gary McKenzie.
Whalen competed at the Third International Ballet and Modern Dance Competition in Nagoya, Japan in 1999. Whalen won The Los Angeles Performing Arts Center Spotlight Award in February 2000 and the Gold Medal at the Youth America Grand Prix in May 2001.
Whalen joined American Ballet Theatre as an apprentice in 2002 and the corps de ballet in April 2003. Her repertory includes the Spanish Dance in Swan Lake and a role in Black Tuesday, as well as roles in all of the Company's full-length ballets. She created a role in Everything Doesn't Happen at Once.