Harris was born Elta Danneel Graul in Lafayette, LA and was raised in the small town of Eunice. Harris was named after her great-grandmother. Her first name, Elta, is a French name, but she always goes by her middle name. The name “Danneel” was inspired by Danneel Street in New Orleans. Her cousin is actress Mary Lou. She moved to Los Angeles and continued her acting training with John Homa, Calmeson and Calmeson, and Craig Wargo.

Before she landed her first acting role, Harris worked as a model with such companies as Big Sexy Hair and Juicy Jeans. She first appeared in a television commercial. The independent film The Plight of Clownana marks her first major acting role. Her other credits include the WB’s What I Like About You, guest appearance on Mad TV and a supporting role in the yet-to-be released indie Rule Number One starring Ed Harris.

Harris is skilled in gymnastics and her musical talents include playing the piano and singing. She relocated to New York in 2004 for her role on One Life to Live.

In 2005, Harris got a recurring role on the hit TV show One Tree Hill, playing Rachel Gatina, a thorn in many of the character’s sides. She went on to become an integral part of the show, featuring in the main credits of the fourth season. However in season five she was only in two episodes due to its format change. Harris revealed to The CW Upfront that she has been contacted about returning to One Tree Hill in season seven. Harris appeared on the cover of the November 2006 edition of Maxim with One Tree Hill costars Hilarie Burton and Sophia Bush. Danneel returned to Tree Hill in the shows seventh season in the fall of 2009.

Since OTH, Danneel has starred in many films such as Fired Up, Harold & Kumar Escape from Guantanamo Bay and Ten Inch Hero where she met her longtime boyfriend, Jensen Ackles. The pair have been dating since 2006.