[1] The season follows Barry facing against his nemesis, the Reverse-Flash, the futuristic alien Despero, the fire Meta Deathstorm and the Negative Forces.

The season is produced by Berlanti Productions, Warner Bros. Television, and DC Entertainment, with Eric Wallace serving as showrunner.

The first "Graphic Novel" of the season, "Armageddon", is a five-episode event featuring multiple actors reprising their Arrowverse roles.

[53] Speaking to the events of the season, showrunner Eric Wallace said that Barry Allen / The Flash would become "the most confident, incredibly powerful, secure team leader".

Wallace noted that one of the graphic novels would feature a new villain who is "a very scary fellow, and when he shows up, we might dip our toes into the world of horror and the supernatural.

"[33] In September 2021, Wallace revealed that Joe West is "going to get an incredibly different perspective on life, and it will lead him to a very big choice.

[33] In August 2021, it was announced that the guest appearances for the "Armageddon" event would include Tom Cavanagh as Eobard Thawne / Reverse-Flash, Javicia Leslie as Batwoman, Brandon Routh as The Atom, Cress Williams as Jefferson Pierce / Black Lightning, Chyler Leigh as Sentinel, Katherine McNamara as Mia Queen, Osric Chau as Ryan Choi, and Neal McDonough as Damien Darhk,[35] with Tony Curran joining the cast as Despero shortly after in an undisclosed capacity.

[59] Courtney Ford cameos as Nora Darhk in the fifth episode while Katie Cassidy, Juliana Harkavy, and Ben Lewis appear through archive footage as Laurel Lance, Dinah Drake, and William Clayton.

Williams said he was "down" to appear since he enjoyed being a part of the "Crisis on Infinite Earths" crossover and felt he and Gustin got along well during their scenes together.

[64] At the virtual 2021 DC FanDome event on October 16, 2021, stars Grant Gustin and Candice Patton revealed the new golden boots as part of the costume in the new season.