Debbie Ocean, the younger sister of the late Danny Ocean, is paroled from prison, and hunts down her former partner-in-crime Lou to convince her to join her heist that she planned while serving her sentence. Debbie and Lou assemble the rest of their team: Rose Weil, a disgraced fashion designer who is deeply in debt; Amita, a jewelry maker and friend of Debbie’s who is eager to move out of her mother’s house and start her own life; Nine Ball, a skilled computer cracker; Constance, a street hustler and pickpocket; and Tammy, another one of Debbie’s friends who has secretly been selling stolen goods out of the garage of her family’s suburban home.
Debbie plans to steal the Toussaint, a $150 million Cartier necklace, from the Met Gala in five weeks, and use Met Gala co-host Daphne Kluger, a dim-witted and snobby actress, as an unwitting mule who will wear the necklace into the gala so they can steal it. After manipulating Daphne into choosing Weil as her stylist, Weil and Amita go to Cartier to convince them to let Daphne wear the necklace, as well as scan it to make a duplicate.
Debbie hunts down her ex-boyfriend Claude Becker, an art dealer who ratted her out to the police when they were discovered for art fraud, which led to her arrest. After threatening him, Debbie manipulates Daphne to invite Becker as her date to the gala. Lou realizes that Debbie is out for revenge on Becker, but Debbie reassures her that everything will be fine.
Weil discovers a flaw in the plan: The Toussaint can only be removed using a special magnet carried by the bodyguards hired by Cartier; Nine Ball enlists her younger sister, Veronica, to build a similar magnet in time for the gala. As the gala begins, Daphne consumes soup that Lou spiked, causing her to vomit in the restroom, where Constance takes the necklace. When the necklace is discovered to be missing, the museum is evacuated and searched; Tammy “finds” the duplicate necklace in order to end the search. Meanwhile, Amita retrieves the real necklace and begins disassembling it. She retools it into several pieces of jewelry, and gives them to Constance to slip to the rest of the team.
The next day, the fake necklace is identified, and John Frazier, an insurance fraud investigator, is called in. Unable to find information, Frazier, who has a history with the Ocean family, discovers that Debbie was present at the gala; however, she has a solid alibi. Debbie assures Frazier that she does not know where the necklace is, but she may know where part of it is. Dropping her dimwitted persona, Daphne is revealed to have been in on the plan, tipped off by Weil’s bad acting, and Debbie and Lou invited her in to keep her from ratting them out. Daphne visits Becker for a romantic evening, where she finds the diamonds planted on him by Debbie during the gala, and sends a picture to Frazier so that he can obtain a warrant to arrest him for stealing the necklace. To further frame Becker, Debbie sells pieces of the necklace to actresses disguised as elderly socialites, who in turn sell the jewelry and deposit the money into an account in his name. Becker is arrested.
As the eight celebrate their victory, Daphne asks Debbie and Lou how they each made so much money from the sale of one necklace. Lou reveals that while the gala was being evacuated, Lou and “The Amazing” Yen were stealing some of the Crown Jewels on display during the Gala, which makes their cuts higher than expected. Each member of the team goes their separate ways with their money: Amita goes to Paris with a man she met on Tinder; Weil pays off her debts and opens her own store; Constance buys a spacious loft in the city and becomes a YouTuber; Tammy expands her business in selling stolen goods; Nine Ball opens a pool bar; Daphne becomes a director; Lou goes on a cross-country road trip; and Debbie returns to Danny’s grave to share a drink with him.