Evans, the daughter of educators, was born in Summit, New Jersey, USA but grew up in Bristol, England. She graduated from University College London after receiving a 2:1 in French and Italian.

Evans had an eight-year relationship with Olivier Picasso, the grandson of painter Pablo Picasso. She briefly enjoyed It-Girl status whilst living with Picasso in Paris and they became engaged. Ioan Gruffudd stated on the Late Late Show with Craig Ferguson that he became engaged to Evans in the early hours of New Year's Day 2006 after Evans gave him an ultimatum. They met during the production of 102 Dalmatians and were dating unofficially until Evans gave an interview revealing their relationship shortly before the premiere of Black Hawk Down to the Daily Express. They married on September 14, 2007 in Mexico.

Gruffudd removed his funding and support of his largest fansite, IoanOnline.com as a result of comments made about Evans on the site, and elsewhere on the Internet, which