At an awards dinner, the newest and brightest star on Broadway — Eve Harrington (Anne Baxter) — is being presented the Sarah Siddons Award for her breakout performance as Cora in Footsteps on the Ceiling. Theatre critic Addison DeWitt (George Sanders) observes the proceedings and, in a sardonic voiceover, recalls how Eve's star rose as quickly as it did.

The film flashes back a year. Margo Channing (Bette Davis) is one of the biggest stars on Broadway, but despite her unmatched success she is beginning to show her age. After a performance one night, Margo's close friend Karen Richards (Celeste Holm), wife of the play's author Lloyd Richards (Hugh Marlowe), meets besotted fan Eve Harrington in the cold alley outside the stage door. Recognizing her from having passed her many times in the alley (as Eve claims to have seen every performance of Margo's current play, Aged in Wood), Karen takes her backstage to meet Margo. Eve tells the group gathered in Margo's dressing room — Karen and Lloyd, Margo's lover Bill Sampson (Gary Merrill) and Margo's maid Birdie (Thelma Ritter) — that she followed Margo's last theatrical tour to New York after seeing her in a play in San Francisco. Margo quickly befriends Eve, moves her into her home and offers Eve a job as her assistant, leaving Birdie, who dislikes Eve, feeling put out.

Eve begins working to supplant Margo, scheming to become her understudy behind Margo's back (which drives wedges between Margo and Lloyd and Margo and Bill) and conspiring with an unsuspecting Karen to cause Margo to miss a performance.

Eve, knowing in advance she will go on, invites the city's theatre critics to the theatre that night. The night is a triumph. Eve makes a pass at Bill, but he rejects her. Following a scathing newspaper column by Addison, Margo and Bill reconcile. The couple dines with the Richards’s that night and Margo and Lloyd make up. That same night at the restaurant, Eve blackmails Karen into telling Lloyd to give her the part of Cora, threatening to tell Margo of Karen's role in Margo's missed performance. Before Karen can act, Margo announces to everyone's surprise that she does not wish to play Cora and would prefer to continue in Aged in Wood, even being willing to take it on tour.

Eve secures the role and attempts to climb higher by using Addison, who is beginning to suspect her veracity. Just before the premiere of her play at the Shubert in New Haven, Eve faces Addison with her next plan—to marry Lloyd after he divorces his wife. Addison is infuriated that Eve has attempted to use him and reveals that he knows her back-story is all lies. Her real name turns out to be not Eve Harrington but Gertrude Slojinski and she had never followed Margo's tour. Before meeting Margo, she had been paid to leave town after her affair with her boss, a brewer in Wisconsin. Addison blackmails her, advising her that in exchange for his silence she now "belongs" to him.

Eve becomes a Broadway star and the film returns to the opening scene in which she is presented with her award. After the awards ceremony, Eve skips a party in her honor and returns home alone where she encounters a young female fan that has slipped into her apartment and fallen asleep. The young girl begins to attend to Eve's needs. "Phoebe" (Barbara Bates), as she calls herself, answers the door to Addison who has returned with Eve's misplaced award. While Eve rests in the other room, Phoebe tries on Eve's wrap and poses in front of a mirror holding the award. The mirrors transform her into countless images of herself.

Oscar
14 Nominations
6 Awards
Best Supporting Actor
Best Director
Best Picture
Best Screenplay
Best Sound
Best Costume

Golden Globes
6 Nominations
1 Award
Best Screenplay
The story of “All About Eve” originated in an anecdote related to Mary Orr by actress Elisabeth Bergner. While performing on Broadway in “The Two Mrs. Carrolls”, Bergner allowed a young fan to become part of her household and employed her as an assistant, but later regretted her generosity when the woman attempted to undermine her. Referring to her only as "the terrible girl," Bergner related the events to Orr, who used it as the basis for her short story "The Wisdom of Eve". In the story, Orr gives the girl a more ruthless character and allows her to succeed in stealing the career of the older actress.

In 1949, Mankiewicz was considering a story about an aging actress and, upon reading The Wisdom of Eve, felt the conniving girl would be a useful added element. He sent a memo to Darryl F. Zanuck saying it "fits in with an original idea [of mine] and can be combined. Superb starring role for Susan Hayward."

Mankiewicz presented a film treatment of the combined stories under the title Best Performance. He changed the main character's name from Margola Cranston to Margo Channing and retained several of Orr's characters.

Zanuck was enthusiastic and provided numerous suggestions for improving the screenplay. He reduced the screenplay by about 50 pages and chose the title “All About Eve” from the opening scenes in which Addison DeWitt says he will soon tell "more of Eve ... All about Eve, in fact.”

Bette Davis was cast as Margo Channing after Claudette Colbert severely injured her back and was forced to withdraw shortly before filming began. Davis, who had recently ended a 19-year association with Warner Bros. after several poorly received films, later commented she had read the script in one sitting and immediately accepted the role after realizing it was one of the best she had ever read. Channing had originally been conceived as genteel and knowingly humorous, but with the casting of Davis, Mankiewicz revised the character to be more abrasive.

Among other actresses considered before Colbert were Mankiewicz's original inspiration, Susan Hayward, rejected by Zanuck as "too young," Marlene Dietrich, dismissed as "too German" and Gertrude Lawrence, who was ruled out of contention when her agent suggested, "Wouldn't it be nice if Gertie sat by the piano and sang?" Zanuck favored Barbara Stanwyck, but she was not available. Tallulah Bankhead and Ingrid Bergman were also considered. Donna Reed and Joan Crawford were also considered for the part but Reed was just twenty-nine years of age at this time making her rather young to play the forty-year-old Margo and Crawford was already working on the film “The Damned Don’t Cry”.

Anne Baxter had spent a decade in supporting roles and had won the Academy Award for Best Supporting Actress for “The Razor’s Edge”. She got the role of Eve Harrington after the first choice, Jeanne Crain, became pregnant. Crain was at the height of her popularity and had established a career playing likable heroines; Zanuck believed she lacked the "bitch virtuosity" required by the part, and audiences would not accept her as a deceitful character.

Mankiewicz greatly admired Thelma Ritter and wrote the character of Birdie Coonan for her after working with her on “A Letter to Three Wives”. As Coonan was the only one immediately suspicious of Eve Harrington, he was confident Ritter would contribute a shrewd characterization casting doubt on Harrington and providing a counterpoint to the more "theatrical" personalities of the other characters.

Marilyn Monroe, relatively unknown at the time, was cast as Miss Caswell, referred to by DeWitt as a "graduate of the Copacabana School of Dramatic Art." Monroe got the part despite Zanuck's initial antipathy and belief she was better suited to comedy.

Praised by critics at the time of its release, “All About Eve” was nominated for 14 Academy Awards (a feat that was unmatched until the 1997 film, “Titanic”) and won six, including Best Picture As of 2010, “All About Eve” is still the only film in Oscar history to receive four female acting nominations (Davis and Baxter as Best Actress, Holm and Ritter as Best Supporting Actress).