Catherine Bell was born on 14 August 1968 in London. She was born to a British father and Iranian mother. At the age of three, she moved to the United States with her mother, and the family settled in Los Angeles.

Originally she wanted to become an artist, but ended up going to UCLA to study medicine, with the intention of becoming a biomedical engineer or a surgeon. Catherine had a change of plans and began modeling part time while in college.

Catherine got her showbiz start in a commercial for American Express, but her big break came playing Isabella Rossellini's body double in "Death Becomes Her".

She was cast in guest spots on shows like Hercules, Dream On, and Friends. But it was a three-line part on the military drama J.A.G. - on an episode in which her character was brutally murdered - that changed it all. Several months after that guest spot, Bell heard that the producers of J.A.G. were looking for a new female lead for the show. So she crossed her fingers and wrote a letter to executive producer Donald P. Bellisario, declaring her suitability for the role of Maj. Sarah "Mac" MacKenzie.

In November 1999, Catherine Bell became the first television star to be presented with The Associates for Breast and Prostate Cancer Research Spirit of Hollywood Award.