Cox was born in Los Angeles, California, the daughter of Meredith and Terry Cox, who is a personal manager. She has one brother, Matthew Cox, who is also an actor. Cox's career as an entertainer started at the age of four, as she appeared as a dancer in several ballet productions and TV specials. She began acting at the age of ten, making appearances in several movies and guest starring on shows such as Baywatch, Star Trek: The Next Generation and Blossom. She also starred in General Hospital from 1993 to 1995 and had a recurring role on the Saturday morning program California Dreams.

Her appearances on various TV shows would lead to her first prime-time starring role as Tiffany Malloy on the sitcom Unhappily Ever After, which ran on the WB 1995–1999.

After Unhappily left the airwaves, she would portray former prostitute Taylor Clayton on the sitcom The Norm Show and star as Nikki White in Nikki, a sitcom vehicle that would last for under two seasons (2000–2002). She starred as Mary Connell on the TV drama Las Vegas from 2003-2007. On May 20 and May 23, 2005, her Las Vegas character crossed over to NBC's cult-favorite soap opera Passions to coincide with the arrival of two new characters introduced on Las Vegas. She is currently the spokesmodel for online gaming giant Sportsbook.com, and is working on Leisure Suit Larry: Box Office Bust, an upcoming video game, and Lonely Street, an upcoming comedy movie starring Robert Patrick, Jay Mohr (her husband), Ernie Hudson and Lindsay Price.

• Lonely Street (2009) (completed) .... Bambi
  
• Leisure Suit Larry: Box Office Bust (2009) (VG) (voice)
• "Ghost Whisperer" .... Nina Haley (1 episode, 2008)
       - Deadbeat Dads (2008) TV episode .... Nina Haley
• "Las Vegas" .... Mary Connell (87 episodes, 2003-2007)
       - Heroes (2007) TV episode .... Mary Connell
       - Junk in the Trunk (2007) TV episode .... Mary Connell
       - Barechested in the Park (2007) TV episode .... Mary Connell
       - The Burning Bedouin (2007) TV episode .... Mary Connell
       - Pharaoh 'Nuff (2007) TV episode .... Mary Connell
        (82 more)
• Fugly (2007) (TV) .... Crystal Stump
• "The Jake Effect" .... Liza Wheeler / ... (7 episodes, 2006)
       - Don't Mess with Sloppy (2006) TV episode .... Liza Wheeler
       - Flight School (2006) TV episode .... Liza Wheeler
       - Only Connect (2006) TV episode .... Liza Wheeler
       - Parent Teacher Conference (2006) TV episode .... Liza Wheeler
       - Pilot (2006) TV episode .... Liza Wheeler
        (2 more)
• "Nikki" .... Nikki White (41 episodes, 2000-2002)
       - My Two Left Feet (2002) TV episode .... Nikki White
       - She Was a Job-Jumper (2002) TV episode .... Nikki White
       - Nikki Can't Wait for Dwight's Birthday (2002) TV episode .... Nikki White
       - To Your Grave (2002) TV episode .... Nikki White
       - Through Thick and Thin (2002) TV episode .... Nikki White
        (36 more)
• Run Ronnie Run (2002) .... Kayla
• "The Norm Show" .... Taylor Clayton / ... (7 episodes, 1999-2001)
  ... aka Norm (USA: new title)
       - Norm vs. Cuba (2001) TV episode .... Taylor Clayton
       - Norm vs. Danny and Shelley (2001) TV episode .... Taylor Clayton
       - Taylor Leaves (2000) TV episode .... Taylor Clayton
       - I've Got a Crush on You (2000) TV episode .... Taylor Clayton
       - Norm vs. the Sacrifice (2000) TV episode .... Taylor Clayton
        (2 more)
• Don's Plum (2001) .... Karen
• "Buzz Lightyear of Star Command" .... Petra (1 episode, 2000)
       - The Plasma Monster (2000) TV episode (voice) .... Petra
• Nutty Professor II: The Klumps (2000) .... Bright Student
  ... aka The Klumps (Australia)