Production notes

47 Ronin was first announced in December 2008, with Keanu Reeves attached to star and Chris Morgan writing the script, which appeared in the 2008 Black List of best unproduced screenplays. According to Variety, the film would "tell a stylized version of the story, mixing fantasy elements of the sort seen in The Lord of the Rings pics, with gritty battle scenes akin to those in films such as Gladiator." Universal Pictures planned to produce the film in 2009 after hiring a director, and entered talks with Carl Rinsch, who has previously filmed "visual and stylish" commercials for various companies, to direct in November of that year. In December 2010, the studio announced that the film would be produced and released in 3D. Between March and April 2011, five Japanese actors - Hiroyuki Sanada, Tadanobu Asano, Rinko Kikuchi, Ko Shibasaki and Jin Akanishi - were cast alongside Reeves, as Universal wanted the film to be more authentic instead of casting actors more recognizable in the United States. Universal provided Rinsch with a production budget of $175 million for the film despite his inexperience with feature-length films, which was considered by The Hollywood Reporter to be a "large-scale, downright risky" move on behalf of the studio.

Principal photography for the film began on March 14, 2011 in Budapest. Origo Film Group contributed to the film. Production moved to Shepperton Studios in the United Kingdom while additional filming in Japan was planned. Reeves revealed that various scenes were first filmed in the Japanese language to familiarize the cast, and were then filmed again in English. The film featured a total of 998 costumes and 400 suits of armour designed by British costume designer Penny Rose, who stated that "We decided to base it on the culture and what the shapes should be—i.e., everyone's in a kimono—but we've thrown a kind of fashion twist at it. And we've made it full of color, which is quite unusual for me." Reshoots were done in London in late August 2012, which were delayed by the 2012 Summer Olympics and the filming of Reeves' directorial debut, Man of Tai Chi. Universal pulled Rinsch from the project during the editing stages in late 2012, with Universal chairwoman Donna Langley taking over the editing process. In addition, the studio added a love scene, extra close-ups and individual lines of dialogue to try and boost Reeves' presence in the film, which "significantly added" to the film's budget.

47 Ronin: Original Motion Picture Soundtrack is a soundtrack album containing the film score composed by Ilan Eshkeri, which was released on December 17, 2013, by Varèse Sarabande.

47 Ronin originally premiered in Japan on December 6, 2013, where it opened to 753 screens and grossed an estimated $1.3 million, opening in third place behind Lupin the 3rd vs. Detective Conan: The Movie and Kaguya-hime no Monogatari (The Tale of Princess Kaguya). Variety reported that the Japanese debut was "troubling", considering the well-known local cast and the fact that the film is loosely based on a famous Japanese tale. The evening tabloid newspaper Nikkan Gendai reported that its dismal performance were "unheard-of numbers" generated by the Japanese distaste for a Hollywood rendition of Chūshingura, which bore little resemblance to the renowned historical epic. In the United States, the film grossed $20.6 million in five days after its release on Christmas Day 2013, opening in ninth place and facing heavy competition from Frozen, The Hobbit: The Desolation of Smaug, Anchorman 2: The Legend Continues, The Wolf of Wall Street, American Hustle, Saving Mr. Banks, The Secret Life of Walter Mitty and The Hunger Games: Catching Fire. In the United Kingdom, the film grossed $2.3 million upon debuting in fifth place. The film was a box-office bomb, unable to recover its $175 million production budget.

47 Ronin was panned by film critics, failing to impress Japanese audiences where studio expectations were high. On Rotten Tomatoes, the film holds a 16% approval rating based on 88 reviews, with an average score of 4.20/10. The critical consensus reads: "47 Ronin is a surprisingly dull fantasy adventure, one that leaves its talented international cast stranded within one-dimensional roles." On Metacritic, the film has a score of 28 out of 100 based on 21 critics, indicating "generally unfavorable" reviews. Audiences polled by CinemaScore gave the film an average grade of "B+" on an A+ to F scale. Kirsten Acuña of Business Insider stated that the film flopped for three reasons: first, it opened in December when there is an oversaturation of films for the Christmas season; second, the film took "too long in the vault" after having undergone editing and lost momentum as a result; and third, audiences had not been drawn to Reeves as an actor since The Matrix Revolutions (which was released ten years prior) and that he had not yet reestablished his stardom prior to making John Wick.