On July 23, 1967, the Detroit Police Department stage a raid on an unlicensed club during a celebration for returning black veterans from the Vietnam War. While suspects are being arrested, a mob forms and starts throwing rocks at the officers before looting nearby stores and starting fires, beginning the 12th Street Riot. With state authorities, elected representatives, and even emergency services unable to maintain any semblance of order, Governor George W. Romney authorizes the Michigan Army National Guard and President Lyndon B. Johnson authorizes Army paratroopers to enter Detroit in order to provide assistance. On the second day of rioting, two cops pursue a fleeing looter. One of them, Philip Krauss, kills the man with a shotgun against orders, but is allowed to remain on duty until his superiors can decide whether to file murder charges.

Detroit received praise for its direction, script and performances, especially those of Poulter, Boyega and Smith. On Rotten Tomatoes, the film has an approval rating of 84% based on 252 reviews, and an average rating of 7.6/10. The site's critical consensus reads, "Detroit delivers a gut-wrenching – and essential – dramatisation of a tragic chapter from America's past that draws distressing parallels to the present." On Metacritic, which assigns a normalized rating to reviews, the film has a weighted average score of 78 out of 100, based on 48 critics, indicating "generally favorable reviews". Audiences polled by CinemaScore gave the film an average grade of "A−" on an A+ to F scale, while comScore reported filmgoers gave an 86% overall positive score and a 63% "definite recommend".

The New Yorker's Richard Brody called the film "a moral failure", saying: "[Bigelow's] intentions come through clearly: to depict an incident—and a climate—of racism, to show that the cruelty of these deeds was multiplied by their ultimate impunity, and to suggest that, in the intervening half-century since the events depicted in the film took place, little has changed. Movies aren’t made with intentions, though; they’re made with people and with equipment, and what Bigelow has her actors do for the benefit of the camera is repellent to imagine."

It was reported at the end of July 2016 that the film had commenced principal photography in Boston during the previous week. Scenes were filmed inside Dedham District Court, in Dorchester, Massachusetts and in Brockton, Massachusetts. In addition, the movie filmed in Detroit during October 2016. The elimination of Michigan's film incentives in 2015 affected the filming locations.

Richard Roeper of Chicago Sun-Times gave the film 4 out of 4 stars and called it one of 2017's best, saying: "Journalist-screenwriter Mark Boal (Bigelow's collaborator on The Hurt Locker and Zero Dark Thirty) does a magnificent job of juggling the multiple storylines and creating fully authentic characters—some flawed, some basically decent, some evil." Writing for Rolling Stone, Peter Travers praised the cast and script, giving the film 3.5/4 stars and saying, "... Detroit is far more than a liberal howl against the escalating toxicity of racism in America. Bigelow, with the same immersive intensity that Christopher Nolan brings to Dunkirk, smacks us down in the middle of a brutal historical event so we can see it – and feel it – for ourselves."