The film stars Dev Patel as Gawain, who sets out on a journey to test his courage and face the Green Knight.

The film received acclaim from critics for its cinematography, music, acting (particularly Patel's), production values, and Lowery's originality, direction, and writing.

They reach a castle inhabited by a Lord who informs him that the Green Chapel is nearby and invites Gawain to stay until closer to Christmas.

When the enemies start to break in, Gawain removes the green girdle, which he had worn the entire time, and his head falls from his shoulders.

He gently runs his finger across Gawain's neck, points past him, and playfully states, "Now, off with your head," as he smiles warmly.

The giants are motion-captured by Andrea Deaskovic, Melinda Dempsey, Aoibheann Garry, Isabel Friosi, Rachel Quinn, Hannah Sjoden, and Lucy Waters It was announced in November 2018 that David Lowery would direct and write a modern retelling of the 14th-century tale Sir Gawain and the Green Knight, with A24, Ley Line Entertainment, and Bron Studios set to finance.

[18] Initially, while writing the script, Lowery did not intend for Morgan le Fay to be Gawain's mother, but felt that altering the story this way allowed for her to be more naturally introduced into the narrative.

Lowery stated that the intercut scenes of le Fay casting the spell that summons the Green Knight were not part of the original screenplay.

[18] The highway robbery is an allusion to the 1975 film Barry Lyndon, while the battlefield where Gawain first encounters the robber is inspired by the Battle of Badon.

Lowery stated that the crew used practical effects to make the Green Knight appear larger, such as mounting Ineson on platforms.

[18] Speaking about the subtle humor and lightness incorporated into the otherwise dark script, Lowery stated that near the end of the film, he directed Ineson to portray the Green Knight as Santa Claus.

"[18] The after-credits scene showing a young girl putting on a crown has been seen as "a tease of an alternate life that Gawain leads as king of Camelot, with his daughter (possibly even mothered by Essel) a sign of the happiness he found.

"[20] The complicated relationship between Morgan le Fay and Gawain written for the film also evoked Lowery's experiences with his mother and needing to be pushed to stand on his own as an adult.

[21] This is further emphasized by Lowery's decision to portray Arthur and Guinevere as sickly, alluding to the waning control of the civilization they represent.

[18] Originally, The Green Knight was scheduled to have its world premiere at the South by Southwest film festival (SXSW) on March 16, 2020,[22] with a full theatrical release following on May 29.

Lowery told the A24 Project podcast and IndieWire that he would prefer The Green Knight to see a theatrical release, but that he was ultimately not in control over whether or not it opened on VOD.

[24] Later, Lowery revealed that he would have been unhappy with the cut of The Green Knight that was set to debut at SXSW, and that he spent six months during the pandemic re-editing the film into something with which he could be satisfied.

[28] After some deliberation, Entertainment opted to release The Green Knight simultaneously in theaters and through Amazon Prime Video on September 24 in the UK.

[31] While the Blu-ray release contained a number of special features that highlighted certain elements of the film's production, no deleted or alternate scenes from The Green Knight were included.

[4][3] In the United States and Canada, The Green Knight was released alongside Jungle Cruise and Stillwater, and was projected to gross around $4 million from 2,790 theaters in its opening weekend.

The site's critics consensus reads, "The Green Knight honors and deconstructs its source material in equal measure, producing an absorbing adventure that casts a fantastical spell.

"[41] Barry Hertz of The Globe and Mail described the film as "a beautiful, haunting and enigmatic work that reckons with the folklore's grave and tragic elements to deliver a masterpiece of blood, sex and magic", and praised Patel's performance as Gawain.

"[43] Keith Watson of Slant Magazine gave the film a score of 2.5 out of 4 stars, describing it as "a self-consciously revisionist take on Camelot lore", and wrote that the film "smooths out the enduring mysteries, opaque psychology, and narrative idiosyncrasies of Sir Gawain and the Green Knight, resulting in a work that's only superficially more daring and enigmatic than its source material.

"[44] Simon Abrams of TheWrap wrote that "while there's a lot of commendable chutzpah and curious longing baked into The Green Knight, the movie's never as compelling as it is unusual.

"[45] In December 2024, Collider ranked the film at number 2 on its list of the "10 Best Fantasy Movies of the 2020s," with Robert Lee III writing "David Lowery has always succeeded in this type of somber, yet undeniably large-scale filmmaking, with The Green Knight easily being the director's magnum opus.