Katherine Williams was born in Honolulu, Hawaii and began her early training with the Hawaii State Ballet. After moving to Maryland with her family, she studied at the Ballet Royale Academy under the direction of Donna Pidel. She was awarded the Youth Grand Prix at the 2003 Finals of the Youth America Grand Prix in New York, and was a Top 12 Finalist at the 2005 Finals. In 2003, she was awarded a full scholarship to the Boston Ballet Summer Dance program. From 2004 to 2006, she attended American Ballet Theatre's Summer Intensives as a National Training Scholar and, in 2006, she also attended the Stiefel and Stars Summer Program.
Williams joined the Jacqueline Kennedy Onassis School at ABT in the Fall of 2005 and remained there until joining the Studio Company in January of 2007. Williams joined American Ballet Theatre as an apprentice in December 2007 and the corps de ballet in June 2008.
Her repertoire with the Company includes a Shade in La Bayadère, one of the Nutcracker's Sisters and the Spanish Dance in Alexei Ratmansky's The Nutcracker, Cinderella, Violente Fairy and the Golden Jewel in The Sleeping Beauty, the Italian Princess in Swan Lake and roles in Airs, Company B, Continuo, In the Upper Room and Jardin aux Lilas. She created roles in AfterEffect and Everything Doesn't Happen at Once. She has also performed as a guest artist for Ballet Hawaii, Baltimore Ballet, Williamsport Civic Ballet, Ballet Royale Institute of Maryland, and Youth America Grand Prix.