Director Frank Darabont first read Stephen King's novella in the 1980 anthology Dark Forces and originally considered adapting The Mist as his directorial debut, but chose The Shawshank Redemption instead.

Darabont set up a first-look deal for The Mist with Paramount Pictures, and by December 2004 he began writing the screenplay; by October 2006 the project moved from Paramount to Dimension Films.

Darabont wrote (but did not film) an opening scene explaining that the mist resulted from a malfunction at the Arrowhead Project's lab, a military experiment opening portals to other dimensions, an origin left vague in King's original novella.

William Sadler, who plays a supporting role in the film, had previously portrayed the lead character David Drayton in a 1986 audiobook version of The Mist.

Darabont wanted to cast Stephen King himself in the supporting role that eventually went to Brian Libby, but King declined because he did not want to travel to film the part.

William Sadler, Jeffrey DeMunn and Brian Libby were all cast in supporting roles, having previously appeared in Darabont's earlier Stephen King adaptations The Shawshank Redemption and The Green Mile.

Filming began in February 2007 at StageWorks of Louisiana in Shreveport, with the exterior shots of the grocery store filmed at the now-demolished Tom's Market in Vivian, Louisiana.

Darabont sought a fluid, ragged documentary style for the film and hired the same camera crew he had used on an episode of The Shield, shooting on grainy 400 ASA Fujifilm rather than digitally.

About 100 extras from the Shreveport area were used, with 60 of them closely integrated into scenes alongside the main cast, and local Louisiana brands like Zapp's potato chips were featured to ground the setting.

David Drayton is seen painting artwork based on Stephen King's The Dark Tower series in the opening scene, created by real-life poster designer Drew Struzan, on whom Darabont reportedly based the Drayton character.

Darabont deliberately kept the score minimal to preserve a documentary feel, and used the Dead Can Dance song 'Host of Seraphim' over the ending, which he felt played like a requiem mass for the human race; Mark Isham composed the original score.

Darabont hired artists Jordu Schell and Bernie Wrightson alongside Greg Nicotero for creature design, choosing CaféFX as visual effects studio on the recommendation of Guillermo del Toro, who had used them for Pan's Labyrinth.

Since the novella described the creatures only briefly, the design team studied past monster designs to avoid duplicating earlier screen creatures, and used puppets to show the cast how the creatures' eyes and mouths would function during motion-capture filming.

The DVD and Blu-ray special editions included a black-and-white version of the film that many fans consider superior to the theatrical color version.

Stephen King praised Darabont's darker altered ending, calling it one that would unsettle studios, and later stated that anyone who spoiled the ending should be 'hung by the neck until dead'.