Nichols was born in the Rogers Park neighborhood of Chicago, Illinois, to a father of Hungarian and Romanian descent and a Texan mother, Maria, of Spanish and Mexican ancestry. She was raised in Naperville, Illinois. She is the oldest of three siblings, having two younger brothers. A rebellious teenager most of her life, Nichols decided to change her attitude and purse acting as a productive outlet.
In 1997, she made her movie debut in the film Vegas Vacation with Chevy Chase which led to other roles in films like. Scream 2, Big Momma's House 2, Friends 'Til the End, Can't Hardly Wait, Jane Austen's Mafia, The Sex Monster and Felon with Stephen Dorff.
In 2001, she played Bahraini Princess, Meriam Al Khalifa in the highly anticipated, true, made for TV movie The Princess and the Marine for which she was nominated for an ALMA Award for Outstanding Actress. At this time, she also starred in the Showtime drama series Resurrection Blvd. from 2000 to 2002 as Victoria Santiago.
Her most famous role to date is she starred in the sixth season of 24 as Special Agent Nadia Yassir in 2007.
Her television credits include guest appearances on Beverly Hills, 90210, Boy Meets World, Charmed, Friends, CSI: Crime Scene Investigation, NCIS, Law & Order: Special Victims Unit, NCIS: Los Angeles, Criminal Minds and six episodes of Cold Case.
She starred in short-lived TV series' like Blind Justice in 2005, In Justice in 2006 and The Gates in 2010.
In 2012 Nichols starred in the ABC TV series GCB, with Leslie Bibb, Kristin Chenoweth, Annie Potts, Jennifer Aspen and Miriam Shor.
In 2017, she joined the cast of Riverdale as Hermione Lodge.