Margaret "Maggie" Fitzgerald, a waitress from a Missouri town in the Ozarks, shows up in the Hit Pit, a run-down Los Angeles gym owned and operated by Frankie Dunn, an old, cantankerous boxing trainer. Maggie asks Frankie to train her, but he initially refuses. Maggie works out tirelessly each day in his gym, even after Frankie tells her she's "too old" to begin a boxing career at her age. Eddie "Scrap-Iron" Dupris, Frankie's friend and employee—and the film's narrator—encourages and helps her.
Frankie's prize prospect, "Big" Willie Little, signs with successful manager Mickey Mack after becoming impatient with Dunn's rejecting offers for a championship bout. With prodding from Scrap and impressed with her persistence, Frankie reluctantly agrees to train Maggie. He warns her that he will teach her only the basics and then find her a manager. Other than Maggie and his employees, the only person Frankie has contact with is a local priest, with whom he spars verbally at daily Mass.
Before her first fight, Frankie leaves Maggie with a random manager in his gym, much to her dismay; upon being told by Scrap that said manager deliberately put her up against his best girl (coaching the novice to lose) to give her an easy win, Frankie rejoins Maggie in the middle of the bout and coaches her instead to an unforeseen victory. A natural, she fights her way up in the women's amateur boxing division with Frankie's coaching, winning many of her lightweight bouts with first-round knockouts. Earning a reputation for her KOs, Frankie must resort to bribery to get other managers to put their trainee fighters up against her.
Eventually, Frankie risks putting her in the junior welterweight class, where her nose is broken in her first match. Frankie comes to establish a paternal bond with Maggie, who substitutes for his estranged daughter. Scrap, concerned when Frankie rejects several offers for big fights, arranges a meeting for her with Mickey Mack at a diner on her 33rd birthday. Out of loyalty, she declines. Frankie begrudgingly accepts a fight for her against a top-ranked opponent in the UK, where he bestows a Gaelic nickname on her. The two travel Europe as she continues to win; Maggie eventually saves up enough of her winnings to buy her mother a house, but she berates Maggie for endangering her government aid, claiming that everyone back home is laughing at her.
Frankie is finally willing to arrange a title fight. He secures Maggie a $1 million match in Las Vegas, Nevada against the WBA women's welterweight champion, Billie "The Blue Bear", a German ex-prostitute who has a reputation as a dirty fighter. Overcoming a shaky start, Maggie begins to dominate the fight, but after a round has ended, Billie knocks her out with an illegal sucker punch from behind after the bell has sounded to indicate the end of the round. Before Frankie can pull the corner stool out of the way which was inappropriately placed on its side by Frankie's assistant, Maggie lands hard on it, breaking her neck and leaving her a ventilator-dependent quadriplegic.
Frankie is shown experiencing the first three of the five stages of grief: first seeking multiple doctors' opinions in denial, then blaming Scrap in anger and later trying to bargain with God through prayer.
In a medical rehabilitation facility, Maggie looks forward to a visit from her family, but they arrive accompanied by an attorney and only after having first visited Disneyland and Universal Studios Hollywood; their only concern is to transfer Maggie's assets to them. She orders them to leave, threatening to sell the house and inform the IRS of her mother's welfare fraud if they ever show their faces again.
As the days pass, Maggie develops bedsores and undergoes an amputation for an infected leg. She asks a favor of Frankie: to help her die, declaring that she got everything she wanted out of life. A horrified Frankie refuses, and Maggie later bites her tongue repeatedly in an attempt to bleed to death, but the medical staff saves her and takes measures to prevent further suicide attempts. The priest Frankie has harassed for 23 years, Father Horvak, warns him that he would never find himself again if he were to go through with Maggie's wishes.
Frankie sneaks in one night, unaware that Scrap is watching from the shadows. Just before administering a fatal injection of adrenaline, he finally tells Maggie the meaning of a nickname he gave her, Mo Chuisle (spelled incorrectly in the film as "mo cuishle"): Irish for "my darling, and my blood" (literally, "my pulse"). He never returns to the gym. Scrap's narration is revealed to be a letter to Frankie's daughter, informing her of her father's true character. The last shot of the film shows Frankie sitting at the counter of a diner where Maggie once took him.Clint Eastwood as Frankie Dunn, a gruff but well-meaning elderly boxing trainer.
Hilary Swank as Mary Margaret "Maggie" Fitzgerald, a determined, aspiring boxer trained up by Frankie Dunn.
Morgan Freeman as Eddie "Scrap-Iron" Dupris, Dunn's gym assistant; an elderly former boxer, he was blinded in one eye in his 109th, and last, fight.
Jay Baruchel as Dangerous Dillard Fighting Flippo Bam-Bam Barch or "Danger", a simple-minded would-be boxer.
Mike Colter as "Big" Willie Little, a boxer whom Dunn has trained for years.
Lucia Rijker as Billie "The Blue Bear" Osterman, a vicious, ex-prostitute boxer.
Brían F. O'Byrne as Father Horvak, the priest of the church which Dunn attends, who cannot stand Dunn.
Anthony Mackie as Shawrelle Berry, an overzealous boxer and frequent tenant of Dunn's gym.
Margo Martindale as Earline Fitzgerald, Maggie's selfish mother.
Riki Lindhome as Mardell Fitzgerald, Maggie's welfare-cheating sister.
Michael Peña as Omar, a boxer and Shawrelle's best friend.
Benito Martinez as Billie's manager
Grant L. Roberts as Billie's cut man, (trainer) trained Hilary Swank off screen for her Academy Award-winning role
Bruce MacVittie as Mickey Mack, a rival of Dunn.
David Powledge as Counterman at Diner
Joe D'Angerio as Cut Man
Aaron Stretch as Himself
Don Familton as Ring Announcer
The film was stuck in so-called "development hell" for years before it was shot. Several studios rejected the project even when Eastwood signed on as actor and director. Even Warner Bros., Eastwood's longtime home base, would not agree to a US$30 million budget. Eastwood persuaded Lakeshore Entertainment's Tom Rosenberg to put up half the budget (as well as handle foreign distribution), with Warner Bros. contributing the rest ($15 million). Eastwood shot the film in less than 40 days between June and July 2004. Filming took place in Los Angeles and film sets at Warner Bros. Studios. The term 'Million Dollar Baby' was from the nose art of a World War II Consolidated B-24 Liberator heavy bomber. Eastwood had his daughter Morgan Colette appear in a brief role as a girl who waves to Swank's character at a gas station.
Eastwood had confidence in Swank's acting background, but upon seeing Swank's small physique, he had concerns, "I just thought, 'Yeah, this gal would be great. If we can get her trained up. If we can get a little bit more bulk on her, to make her look like a fighter'...She was like a feather. But what happened is, she had this great work ethic."
Consequently, to prepare for her role, Swank underwent extensive training in the ring and weight room gaining 19 pounds of muscle, aided by professional trainer Grant L Roberts. She trained for nearly five hours every day, winding up with a potentially life-threatening staphylococcus infection. She did not tell Eastwood about the infection because she thought it would be out of character for Maggie.
Million Dollar Baby initially had a limited release, opening in eight theaters in December 2004. In its later wide release opening, the film earned $12,265,482 in North America and quickly became a box-office hit both domestically and internationally. It grossed $216,763,646 in theaters; $100,492,203 in the United States, and $116,271,443 overseas. The film played in theaters for six and a half months.
The film received critical acclaim, with a 91% rating on Rotten Tomatoes and an 86 out of 100 score on Metacritic, meaning "universal acclaim". Roger Ebert of the Chicago Sun Times gave the film four stars and stated that "Clint Eastwood's Million Dollar Baby is a masterpiece, pure and simple," listing it as the best film of 2004. Michael Medved stated: "My main objection to Million Dollar Baby always centered on its misleading marketing, and effort by Warner Brothers to sell it as a movie about a female Rocky, with barely a hint of the pitch-dark substance that led Andrew Sarris of the New York Observer . . . to declare that 'no movie in my memory has depressed me more than Million Dollar Baby.'"
In early 2005, the film sparked controversy when some disability rights activists protested the ending. Wesley J. Smith in The Weekly Standard also criticized the film for its ending and for missed opportunities; Smith said, "The movie could have ended with Maggie triumphing once again, perhaps having obtained an education and becoming a teacher; or, opening a business managing boxers; or perhaps, receiving a standing ovation as an inspirational speaker."
Eastwood responded to the criticism by saying the film was about the American dream. In an interview with the Los Angeles Times, Eastwood distanced himself from the actions of characters in his films, noting, "I've gone around in movies blowing people away with a .44 Magnum. But that doesn't mean I think that's a proper thing to do". Roger Ebert stated that "a movie is not good or bad because of its content, but because of how it handles its content. Million Dollar Baby is classical in the clean, clear, strong lines of its story and characters, and had an enormous emotional impact".
Some commentators criticized the fact that the phrase mo chuisle, a term of endearment meaning literally "my pulse", and generally "my darling", was misspelled in the film as Mo Cuishle, as shown on the back of Maggie's robe. It is translated in the film as "my darling, my blood", although an Irish Gaelic translation site states that it is always translated as "pulse", not as "blood". The original phrase is short for a chuisle mo chroí, meaning "O pulse of my heart". The film has been praised, however, for stirring renewed interest in the Irish language in the U.S.
Multiple critics found a plot twist in the film to be particularly significant in discussion of the film's merits, and therefore wrote it was difficult to write proper reviews of the film. When describing the plot of the film, Ebert gave a spoiler warning. He noted in his reviews the difficulty of discussing the film without discussing details of the plot, saying that even warning about spoilers would itself be a spoiler. Susan Wloszczyna of USA Today said the film "packs a surprise plot twist" and said "spoilsports already have begun to leak details about this drama", saying "the urge to divulge the story's secrets will only grow worse when the film finally goes nationwide." Wloszczyna noted that David Thomson of The Independent "offered readers only a hint of the story basics" and said "most reviewers have coddled the sports saga with similar care..." Wloszczyna quoted Thomson as saying, "My great wish always, which is difficult to achieve, is to go in knowing nothing about a film."
Jeffrey Overstreet of Christianity Today avoided revealing plot details, stating that while knowing the nature of the third part would not ruin the film, it would alter the experience significantly. Mark Moring of Christianity Today said, "Who wants to watch a movie when you know how it ends? We've actually had to wrestle with that question around here lately..." Moring said, "We wondered if our 'moral obligation' to warn Christians about the potentially disturbing subject matter somehow 'trumped' our professional commitment to avoid plot spoilers—especially the worst plot spoiler of all: divulging the end. After some discussion, we agreed that the right decision was to not give away the end to Million Dollar Baby."
Michael Atkinson of The Village Voice said the film had a "spoiler-spawning shift in narrative." Ian Grey of Baltimore City Paper said the last act seems to be from another film at first, and said "Naming this misfortune and its consequences, however, would be an unforgivable spoiler."
Million Dollar Baby received the award for Best Picture of 2004 at the 77th Academy Awards. Clint Eastwood was awarded his second Best Director Oscar for the film, and also received a Best Actor in a Leading Role nomination. Hilary Swank and Morgan Freeman received Best Actress in a Leading Role and Best Actor in a Supporting Role Oscars, respectively. Joel Cox, Eastwood's editor for many years, was nominated for Best Film Editing, and Paul Haggis was nominated for the Best Adapted Screenplay award. The film was named the third "Best Film of the 21st Century So Far" in 2017 by The New York Times.
The film was released on VHS and DVD on July 12, 2005, and all editions of the Region 1 DVD, except for the "Deluxe Edition", came with a paperback copy of the book Rope Burns: Stories from the Corner. An HD DVD release was issued on April 18, 2006. The Blu-ray Disc version was released on November 14, 2006. It was the first Best Picture winner released on either high-definition optical disc format in the U.S.; it and Unforgiven were the only ones released in the U.S. on HD DVD prior to the first one released in the U.S. on Blu-ray, Crash.