Carroll Baker was born and raised in Johnstown, Pennsylvania, in a Roman Catholic family, the daughter of Edith Gertrude (nee Duffy) and William Watson Baker, a traveling salesman. She is of Polish descent, which has given rise to a rumor that her birth name was Karolina Piekarski. However, this currently cannot be substantiated by known records. Baker's parents separated when she was eight years old, and she moved with her mother and younger sister, Virginia, to Turtle Creek, Pennsylvania.

Baker separated from her second husband, Jack Garfein, in 1967, and moved to Europe with her two children to pursue a career there after struggling to find work in Hollywood. Eventually settling in Rome, Italy, Baker became fluent in Italian and spent the next several years starring in hard-edged Italian thrillers, exploitation, and horror films. In 1966, Baker had been invited to the Venice International Film Festival, where she met director Marco Ferreri, who asked her to play the lead role in Her Harem (1967). This was followed with the horror films The Sweet Body of Deborah (1968) and The Devil Has Seven Faces (1971). Baker also starred in So Sweet... So Perverse (1969), Paranoia (1969), A Quiet Place to Kill (1970), and Il coltello di ghiaccio (Knife of Ice) (1972), all horror films directed by Italian filmmaker Umberto Lenzi.  Many of these films feature her in roles as distressed women, and often showed Baker in nude scenes, which few major Hollywood actors were willing to do at the time. Baker became a favorite of Umberto Lenzi, with her best-known role being in the aforementioned Paranoia, where she played a wealthy widow tormented by two sadistic siblings. In his review of Paranoia, Roger Ebert said: "Carroll Baker, who was a Hollywood sex symbol (for some, it is said) until she sued Joe Levine and got blacklisted, has been around. She may not be an actress, but she can act. In The Carpetbaggers, there was a nice wholesome vulgarity to her performance. She is not intrinsically as bad as she appears in Paranoia. I think maybe she was saying the hell with it and having a good time." As with Paranoia, the majority of the films she made in Italy received poor critical reception in the United States, though they afforded Baker--who had left Hollywood in debt and with two children to support-- an income, as well as fame abroad. In retrospect, Baker commented on her career in Italy and on her exploitation film roles, saying: "I think I made more films [there] than I made in Hollywood, but the mentality is different. What they think is wonderful is not what we might ... it was marvelous for me because it really brought me back to life, and it gave me a whole new outlook. It's wonderful to know about a different world."  She followed her roles in Lenzi's films with a leading role in Corrado Farina's Baba Yaga (1973) as the titular witch, alongside Isabelle De Funes and George Eastman. TV Guide referred to the film as an "exceptionally handsome example of 1970s Italian pop-exploitation filmmaking sweetened by Piero Umilani's lounge-jazz score," and praised Baker's performance, but noted that she was "physically wrong for the role; her elaborate lace-and-beribboned costumes sometimes make her look more like a fleshy Miss Havisham than a sleekly predatory sorceress".

Did she star with anyone noteworthy?