The 2021 Double or Nothing was the third annual Double or Nothing professional wrestling pay-per-view (PPV) event produced by All Elite Wrestling (AEW). It took place during Memorial Day weekend on May 30, 2021. The event was primarily held at Daily's Place in Jacksonville, Florida; however, portions of the main event match were pre-taped at the nearby TIAA Bank Field. It was the first Double or Nothing event to be held on a Sunday. It was also AEW's last PPV to be held at Daily's Place during the COVID-19 pandemic. Double or Nothing was originally scheduled to be held at the MGM Grand Garden Arena in Paradise, Nevada on May 29, but was moved to Daily's Place and pushed back a day due to the pandemic. The event aired through traditional PPV providers, as well as on B/R Live in North America and FITE TV internationally.

Ten matches were contested at the event, including one on The Buy In pre-show. In the main event, The Inner Circle (Chris Jericho, Jake Hager, Sammy Guevara, Santana, and Ortiz) defeated The Pinnacle (MJF, Wardlow, Shawn Spears, Cash Wheeler, and Dax Harwood) in a Stadium Stampede match; had The Inner Circle lost, they would have been forced to disband. In other prominent matches, Kenny Omega defeated Orange Cassidy and Pac in a three-way match to retain the AEW World Championship, Dr. Britt Baker, D.M.D. defeated Hikaru Shida by submission to win the AEW Women's World Championship, Sting and Darby Allin defeated Scorpio Sky and Ethan Page, and The Young Bucks (Matt Jackson and Nick Jackson) defeated Jon Moxley and Eddie Kingston to retain the AEW World Tag Team Championship. The event was also notable for the surprise appearances of Lio Rush and Mark Henry, making their AEW debut, as well as a cameo appearance by Konnan during the Stadium Stampede match.

Double or Nothing drew 5,200 attendees, making it AEW's highest attended event since the start of the pandemic up to that point, and also making it the first AEW event to emanate with a full capacity crowd since the start of the pandemic. It also garnered an estimated 135,000 pay-per-view buys, and generated over $6 million in revenue, which in turn made it the third highest grossing non-WWE professional wrestling PPV event since 1999.