Kym Karath was born in Los Angeles, California in 1958 and began her acting career at the age of 3, appearing in Spencer's Mountain with Henry Fonda and Maureen O'Hara. She continued her child acting career in The Thrill of It All with Doris Day and James Garner, and Good Neighbor Sam with Jack Lemmon before winning the role of the youngest Von Trapp daughter.

After The Sound of Music, Kym continued acting, appearing over the years in such television shows in Dr. Kildare, Lassie, My Three Sons, Lost In Space, Family Affair, and The Brady Bunch before taking time off to pursue her education.

Graduating from USC with her degree in Humanities, Kym made television appearances in such shows as Archie Bunker's Place, and Midnight Offerings, before moving to Paris to model and study art history. Upon returning to the States, Kym appeared in All My Children and various print ads before taking time off to raise her son, Eric. She is now resuming her acting career in Los Angeles, California.