Krista Allen was born in Ventura, California. Allen has an older brother, Dalton Earl Allen, Jr. She grew up in Houston and later lived in Austin, Texas, going to school at Austin Community College and majoring in education. Krista transferred to, and graduated from, the University of Texas with an education degree. She considered teaching as a profession, interning as a kindergarten teacher, but decided to move back to California and pursue an acting career. Allen also is a certified yoga instructor.
Allen first gained attention playing the lead role in the erotic cable television series Emmanuelle in Space (1994)
She appeared on the television shows Days of Our Lives in the role of Billie Reed from 1996–2000, and Baywatch as Jenna Avid (2000-2001).
Allen played a sexy virtual reality character Maitreya/Jade Blue Afterglow in an episode of The X-Files, and made a brief appearance as the "Elevator Girl" in the Jim Carrey comedy Liar Liar.
In 2002, she appeared in an episode of Friends, "The One Where Joey Dates Rachel" as Joey's girlfriend Mable. In 2005 she appeared in the short-lived Fox sitcom Head Cases. In both Smallville and Mutant X, Allen played a woman who could control men with her sex pheromones. In 2001 Allen guest starred in supernatural TV series Charmed as "The Oracle" for three episodes, She also appeared in Toby Keith's video "A Little Too Late", and had a small role in CSI: Crime Scene Investigation as Kristy Hopkins, a hooker who caught the eye of Nick Stokes, in the pilot episode on October 6, 2000. She returned later in the first season as a murder victim.
In 2002, she had a role in Confessions of a Dangerous Mind.
In 2005, she was one of the stars of HBO's Unscripted, playing herself as an actress who struggles to overcome her sex symbol status in order to win more serious roles.
Allen had a recurring role on the ABC series What About Brian as Bridget, a reluctant but potential love interest for the main character Brian, played by Barry Watson.
In 2007, Allen appeared in the ABC reality television series Fast Cars and Superstars: The Gillette Young Guns Celebrity Race, featuring a dozen celebrities in a stock car racing competition. In the first round, she matched up against skateboarder Tony Hawk and rodeo champion Ty Murray. Allen appeared on the second season of Denise Richards: It's Complicated which premiered on June 7, 2009. Allen also appeared on an episode of NBC's Love Bites in 2011.
In August 2015, Allen began appearing as Lydia Marlowe on The CW series Significant Mother.
In addition to acting, Allen also has done nude modeling, being featured in Spanish magazine, Interviu, and French magazine, Newlook. Allen was featured in Maxim magazine's Girls of Maxim gallery and was Named #70 on the Maxim "Hot 100 of 2005" list.
Allen had a T-shirt line called Superexcellent for several years.
Allen is vegan.
On September 14, 1996, she married Justin Moritt, a production manager and producer. She gave birth to her first child at age 26, a son named Jakob Nolan Moritt (aka Jake Moritt) on July 12, 1997. The couple later divorced in 1999.
On October 10, 2010, she married Mams Taylor, an Iranian rapper. They separated in April 2011 and Allen filed for divorce at Los Angeles County Superior Court on February 12, 2012.