Romijn (pronounced "Ro-Maine" in the USA but the proper Dutch pronunciation is "Ro-mine") was born in Berkeley, California, the daughter of Elizabeth (née Kuizenga), a public school English teacher and textbook author, and Jaap Romijn, a custom furniture maker. Her father, a native of Barneveld, The Netherlands, is Dutch, and her mother is a second-generation Dutch American who met Romijn's father while studying in Europe. Romijn's maternal grandfather, Dr. Henry B. Kuizenga, was a Presbyterian minister and seminary professor. Her maternal grandmother is first cousins with Dorothy Letterman, David Letterman's mother. Many sources say that she was once nicknamed the "Jolly Blonde Giant" but she has admitted to making that up 'for a laugh'. While studying music (voice) at the University of California, Santa Cruz, she became involved with fashion modeling and eventually moved to Paris for more than two years.
Among other jobs, Romijn modeled for the swimsuit issue of Sports Illustrated and for Victoria's Secret. She also was the host of MTV's House of Style from 1998 to 2000. Rebecca is a fixture on annual lists of the world's most beautiful women by publications such as Maxim (2003-2007), AskMen.com (2001-,2003, 2005-2006) and FHM (2000-2005). She also appeared as a guest in the animated talk show Space Ghost Coast to Coast in an episode titled "Chinatown."
In 2000's X-Men, Romijn had her first major movie role as "Mystique"; she returned to the role in 2003's sequel X2: X-Men United, and again for X-Men: The Last Stand (2006). In these movies her costume consisted of blue makeup and some strategically placed prosthetics on her otherwise nude body. In X2: X-Men United she shows up in a bar in one scene in her "normal" look, and also in X-Men: The Last Stand, she appears as a dark-haired "de-powered" Mystique. She had her first leading role in Brian De Palma's Femme Fatale (2002). She also has starred in movies such as Rollerball, The Punisher and Godsend. She played the leading role in Pepper Dennis, a short-lived TV series on The WB. This series showcased Romijn's talents for comedy, singing, modeling, drama, and adventure.
In January 2007, Romijn made her first appearance on the ABC series Ugly Betty as a full time regular. She plays Alexis Meade, a male-to-female transsexual and the sibling of lead character Daniel Meade. In April 2008, however, it was reported that Romijn would only be appearing as a recurring character in season 3 due to a change in direction by the writing staff. In November 2007, Romijn made a guest appearance on the ABC series Carpoolers, where she played the ex-wife of the character Laird, played by her real-life husband Jerry O'Connell.