The film stars Jamie Lee Curtis, Judy Greer, Andi Matichak, Will Patton, Thomas Mann, Jim Cummings, and Anthony Michael Hall.

Jason Blum served as a producer on the film through his Blumhouse Productions banner, alongside Malek Akkad and Bill Block.

Following a year delay due to the COVID-19 pandemic, Halloween Kills had its world premiere at the 78th Venice International Film Festival on September 8, 2021, and was theatrically released in the United States on October 15, 2021, by Universal Pictures.

On October 31, 1978, rookie police officer Frank Hawkins accidentally shoots his partner dead while trying to save him from Michael Myers.

Forty years later, on October 31, 2018, after being stabbed and left to die by Dr. Ranbir Sartain, Hawkins is found by Cameron Elam, who calls an ambulance.

While warning the Haddonfield community to stay inside their houses, Marion and bar patrons Vanessa and Marcus are killed by Michael.

Tommy takes Lindsey to the hospital and reunites with former Haddonfield sheriff Leigh Brackett, whose daughter Annie was killed in 1978, and informs Laurie about Michael's survival.

As Michael prepares to kill Allyson, Karen appears and stabs him in the back with a pitchfork, steals his mask, and taunts him to follow her.

Also appearing in the film are Carmela McNeal as Vanessa, a bar patron; Michael Smallwood as Marcus, Vanessa's husband; Omar Dorsey as Barker, Haddonfield's current sheriff; Jim Cummings as Pete McCabe, Hawkins' partner whom Hawkins accidentally killed in 1978;[7] Scott MacArthur and Michael McDonald as Big John and Little John, the current owners of Myers' house; Ross Bacon as Lance Tivoli, an escaped convict from Smith's Grove Psychiatric Hospital who is mistaken with Michael; Brian F. Durkin as Graham, Haddonfield's deputy sheriff; Lenny Clarke and Diva Tyler as Phil and Sondra Dickerson (Diva was the caretaker in the previous film), Laurie's neighbors; the Levesque Triplets (Andrea Levesque, Arianna Levesque and Athena Levesque) as singing triplets in the bar; Mike Dupree as a singing ventriloquist; and Elaine Nalee as a helpful neighbor from Tommy's mob.

[9] P. J. Soles and Nancy Kyes appear as Lynda Van Der Klok and Annie Brackett, respectively, in archive footage from the 1978 film.

Kyes is also shown in repurposed archive footage from the now non-canon Halloween II (1981), in which Brackett sees Annie's dead body.

The producers were unable to secure the likeness of original actor John Michael Graham for the film and instead used a real high school yearbook photograph of Odenkirk after discovering their resemblance.

[13] In February 2019, Collider exclusively confirmed Scott Teems was in talks to write the script, having collaborated with Blumhouse Productions on several projects in development.

Blum, Malek Akkad and Bill Block returned as producers, while Jamie Lee Curtis, Judy Greer and Andi Matichak reprised their roles.

[23] On August 26, 2019, it was announced that Anthony Michael Hall would join the cast as Tommy Doyle, a character portrayed by Brian Andrews in the original Halloween film.

[24] Paul Rudd, who played Doyle in Halloween: The Curse of Michael Myers, was approached to reprise his role, but declined as he was unavailable due to his commitments to Ghostbusters: Afterlife.

[29] Jibrail Nantambu is set to reprise his role as Julian from the previous film; while Victoria Paige Watkins and Brian F. Durkin were confirmed as members of the cast.

[46] The final confrontation where Michael murders the mob formed by Tommy Doyle was filmed on a "lazy susan"-esque rotating stage that circled around the camera.

[47] In an interview, Andi Matichak revealed that filming was planned back-to-back with Halloween Ends but did not occur due to the "intense schedule".

[3][4] In the United States and Canada, Halloween Kills was released alongside The Last Duel, and was initially projected to gross $35–40 million from 3,700 theaters in its opening weekend.

The site's critical consensus reads, "Halloween Kills should satisfy fans in search of brute slasher thrills, but in terms of advancing the franchise, it's a bit less than the sum of its bloody parts.

[64] Barry Hertz of The Globe and Mail was positive in his review, saying that the film was "brimming with odd decisions", but added: "there is something entertaining, or maybe just enjoyably puzzling, about what Gordon Green and McBride think a Michael Myers movie could or ought to be.

"[71] Brian Truitt of USA Today gave the film 2.5/4 stars, saying that it was "gruesomely brutal as a night spent with Michael Myers should be", but added that it "loses some of its skull-crushing effectiveness juggling rampant carnage and social commentary.

[74] David Fear of Rolling Stone wrote: "Kills comes incredibly close to erasing every ounce of good will that Green's revolutionary redo built up.

"[75] Brian Lowry of CNN said that the film was "odd on various levels, starting with the wholly misguided attempt to weave a half-baked message into its bloody mayhem", and wrote: "If the previous movie conjured a bit of excitement by eradicating everything that had transpired after the original, that sense of novelty has quickly worn off.

"[76] Richard Roeper of the Chicago Sun-Times gave the film a score of 2/4 stars, describing it as a "thudding disappointment" and "an inconsistent, sloppy mess.

"[77] Kevin Maher of The Times gave the film 1/5 stars, describing it as a "depressingly mechanical gorefest" that "has nothing to offer the sentient viewer".

"[79] Linda Marric of The Jewish Chronicle also gave the film 2/5 stars, deeming it "a shambolic, risible mess which is further hampered by a total absence of genuinely scary bits.

"[82] In July 2019, the film was announced alongside a sequel titled Halloween Ends, which was released on October 14, 2022, in theaters and on paid tiers of Peacock for 60 days.