It stars Sydney Sweeney (who also produced), Álvaro Morte, Benedetta Porcaroli, Dora Romano, Giorgio Colangeli, and Simona Tabasco.

The plot focuses on a young novice nun, who is invited to reside at a picturesque Italian convent, but slowly realizes the terrifying secrets it harbors.

Sister Mary sneaks into a superior's bedroom at night and steals a ring of keys to escape through the locked gates of a Catholic convent.

[9] Following her breakout role in the television series Euphoria, Sweeney purchased the rights to the screenplay and approached frequent collaborator Michael Mohan to direct.

[11] Mohan stated that the script originally featured a cast of high school girls, not nuns, and was changed to better suit Sweeney and audience expectations.

[12] In February 2023, Álvaro Morte, Benedetta Porcaroli, Dora Romano, Giorgio Colangeli and Simona Tabasco joined the cast of the film.

[5][4] In the United States and Canada, Immaculate was released alongside Ghostbusters: Frozen Empire and Late Night with the Devil, and was projected to gross around $5 million from 2,354 theaters in its opening weekend.

The website's consensus reads: "Immaculate in conception if not always in execution, this religiously themed horror outing is saved by a divine performance from Sydney Sweeney.

[25] Tim Robey of The Telegraph awarded the film three stars out of five, saying that "Sydney Sweeney's pregnant-nun horror takes time to deliver… Only at the very end does Immaculate deliver, so to speak, on some of (its) hinted-at promise.

"[30] Due to sharing similar premises (and a common Italian setting) and released at about the same time, Immaculate and The First Omen have been dubbed as "twin" films.

[31] Some reviewers have suggested both films explore the issue of female bodily autonomy, depicting the "systemic control of women's bodies reduced to vessels".

[32] Bilge Ebiri of Vulture wrote "why should anyone be surprised that suddenly, in the wake of the Supreme Court's overturning of Roe v. Wade, as state after state attempts to enact religious laws depriving women of bodily agency, America is getting horror movies about people forced into monstrous births by religious institutions worried about their growing irrelevance".

Speaking with Fangoria, director Mohan recited a story wherein his family stopped attending church after hearing a pro-life sermon; however he held that the movie was not intended to have a social message.

[12] The article reads And though the film – which is, at the end of the day, about a forced birth by a religious institution laying claim to a woman's body – is already getting its share of blowback from certain conservative corners of the internet, Mohan is unbothered.

[41][42][43] Others noted the aesthetic and thematic influences of 1970s European horror cinema, including directors Dario Argento, Mario Bava, Lucio Fulci, and Roman Polanski.