Released in North America on August 3, 2001 and was a commercial success, grossing $165.3 million worldwide. The film was followed by a sequel, The Princess Diaries 2: Royal Engagement, released in August 2004.
Teenager Mia Thermopolis lives with her artist mother, Helen, and her cat, Fat Louie, in a remodeled San Francisco firehouse. A somewhat awkward and unpopular girl, Mia is terrified of public speaking, and often wishes to be "invisible". She has a crush on Josh Bryant, but is frequently teased by both Josh and his cheerleader girlfriend, Lana Thomas. Mia’s only friendships are in the form of the equally unpopular Lilly Moscovitz and Lilly's brother, Michael, who secretly has a crush on Mia.
Just before her sixteenth birthday, Mia learns that her paternal grandmother, Clarisse, is visiting from Genovia, a small European kingdom. When Mia goes to meet her at a large house (later revealed to be the Genovian consulate), Clarisse reveals she is actually Queen Clarisse Renaldi, and that her son, Mia’s late father, was Crown Prince of Genovia. Mia is stunned to learn she is a princess and heir to the Genovian throne. In shock, Mia runs home and angrily confronts her mother, who explains she had planned to tell Mia on her eighteenth birthday, but that her father’s death has forced the matter. Queen Clarisse visits and explains that if Mia refuses the throne, Genovia will be without a ruler (A subplot involves a scheming baron and his unsightly baroness quietly rooting for Mia's downfall.) Helen persuades a hesitant Mia to attend "princess lessons" with the Queen, telling her she does not have to make her decision until the upcoming Genovian Independence Day ball.
Mia is given a glamorous makeover, the use of a limousine, and a bodyguard (the Queen’s head of security, Joe.) This and Mia's frequent absences for the lessons make Lilly suspicious and jealous, and she accuses Mia of trying to be like the popular girls. Mia breaks down and tells Lilly everything and swears her to secrecy. However, the San Francisco Chronicle learns that Mia is the Genovian Crown Princess after royal hairdresser Paolo breaks his confidentiality agreement (so his work would be known,) causing a press frenzy, and a sudden surge in popularity at school for Mia. In a craven urge for fame, many of her classmates bluff that they are friends of the princess to reporters.
At a state dinner, Mia embarrasses herself with her clumsiness, delighting her rivals for the crown. However, all is not lost, as the situation amuses a stuffy diplomat, and the Queen tells Mia the next day that she found it fun. Deciding it is time the two bonded as grandmother and granddaughter, the Queen allows Mia to take her out for the day to the Musée Mécanique, an amusement arcade. The day almost ends terribly when Mia's car stalls a hill and rams backward into a cable car, but Queen Clarisse saves the day by "appointing" the attending police officer and the tram driver to the Genovian "Order of the Rose" (something she clearly made up on the spot), flattering them into dropping any charges. Mia sees this and is impressed with her grandmother.
Later, Mia is delighted when Josh Bryant invites her to a beach party, but her acceptance hurts Lilly and Michael, with whom she had plans. Things go awry when the press arrive, tipped off by Lana. Josh uses Mia to get his fifteen minutes of fame by publicly kissing her, while Lana tricks Mia into changing in a tent, pulling it away as the paparazzi arrive, giving them a scandalous shot of Mia in a towel. The photos appear on tabloid covers the next day, leaving Queen Clarisse furious at Mia. A humiliated Mia tells Clarisse that she is renouncing the throne, feeling she is nowhere near ready to be a true princess. Joe later reminds the Queen that although Mia is a princess, she is still a teenager, and her granddaughter.
Back at school, Mia attempts to rescue her friendships with Lilly and Michael by inviting them to the Genovian Independence Day Ball, and gets back at Josh by hitting a baseball into his groin during gym class. She finally stands up to Lana in defense of Jeremiah, whom Lana was mocking, by smearing ice-cream on Lana's cheerleader outfit and declaring that, while Mia has a chance to grow out of her awkward ways, Lana will always be a jerk. While Lilly is excited at the prospect of attending a royal ball, Michael, brokenhearted over Mia's initial feelings for Josh, turns her down. Clarisse apologizes to Mia for being furious at her over the beach incident, and states that she must publicly announce her decision to become princess of Genovia. Mia, terrified at this large responsibility placed upon her, plans to run away. However, when she finds a letter from her late father, his touching words make her change her mind, and she makes her way to the ball. Mia’s car breaks down in the rain, but she is rescued by Joe, who had suspected she was going to run.
When they arrive, a drenched and untidy Mia voices her acceptance of her role as Princess of Genovia. After changing into an opulent ballgown, Mia accompanies Clarisse to the ballroom, where she is formally introduced and invited to dance. Michael, accepting an apologetic gift from Mia (a pizza with M & M candies cleverly topped to say "sorry",) arrives at the ball, and after a quick dance, they adjourn to the courtyard. Mia confesses her feelings to him, stating that even when she was constantly teased and embarrassed at school, Michael liked her for who she truly was. Mia shares her first kiss with Michael, while Clarisse and Joe are seen holding hands. In the final scene, Mia is shown on a private plane with Fat Louie, writing in her diary, explaining that she is moving with her mother to Genovia, just as the beautiful royal palace and landscape come into view below.Anne Hathaway as Amelia "Mia"
Julie Andrews as Queen Clarisse Renaldi
Heather Matarazzo as Lilly Moscovitz
Héctor Elizondo as Joseph "Joe"
Mandy Moore as Lana Thomas
Caroline Goodall as Helen Thermopolis, Mia's Mother
Robert Schwartzman as Michael Moscovitz
Erik von Detten as Josh Bryant
Patrick Flueger as Jeremiah Hart
Sean O'Bryan as Patrick O'Connell, Mia's Debate teacher
Sandra Oh as Vice Principal Geraldine Gupta
Kathleen Marshall as Charlotte Kutaway
Mindy Burbano as Gym teacher Ms.Anita Harbula
René Auberjonois as Voice of Philippe Renaldi
Larry Miller as Paolo Puttanesca
The film was produced by Whitney Houston and Debra Martin Chase and directed by Garry Marshall. Anne Hathaway was hired for the role of Mia because Garry Marshall's granddaughters saw her audition tape and said she had the best "princess hair." According to Hathaway, the first choice for the role of Mia Thermopolis was Liv Tyler, but the studio preferred to cast unfamiliar faces.
Héctor Elizondo, who appears in all the films which Marshall directs, plays Joe, the head of Genovian security. Garry Marshall's daughter, Kathleen, plays Clarisse's secretary Charlotte Kutaway. Charlotte's surname is mentioned only in the credits, and Garry Marshall says it is a reference to how she is often used in cutaway shots. In one scene, Robert Schwartzman's real-life group Rooney makes a cameo playing a garage band named Flypaper, whose lead singer is Michael, played by Schwartzman. The Cable car tourist was portrayed by Kathy Garver.
The book was set in New York City, but the film's location was changed to San Francisco. West Coast radio personalities Mark & Brian appear as themselves.
The film opened in 2,537 theaters in North America and grossed $22,862,269 in its opening weekend. It grossed $165,335,153 worldwide—$108,248,956 in North America and $57,086,197 in other territories.
Review aggregator Rotten Tomatoes reports that 47% of 113 film critics gave the film a positive review, with a rating average of 5.2 out of 10. The site's consensus reads, "A charming, if familiar, makeover movie for young teenage girls." Metacritic, which assigns a weighted average score out of 100 to reviews from mainstream critics, gives the film a score of 52 based on 27 reviews.
A sequel, The Princess Diaries 2: Royal Engagement, was released on August 11, 2004.