Harry Potter years (2001–present)
Watson was eleven years old when Harry Potter and the Philosopher's Stone was released. In her first major interview with the BBC in 2001, Watson stated she particularly enjoyed doing the stunts, especially in the scene when her character is chased by a troll and has to dart under sinks and run through the legs of bigger actors. Later, she added that her parents did their best to make her feel comfortable, and that her biggest thrill was getting to know all her adult co-stars, including Maggie Smith, Alan Rickman, and Robbie Coltrane, among others.
A year later, Watson again starred as Hermione in the 2002 film Chamber of Secrets, the second installment of the Harry Potter film series. Now twelve years old, she said that success had not changed her, and that she was happy to know the filming process now instead of being new to everything as she was in the first film. In a 2007 interview, Watson added that in both films, she lost several baby teeth and had to wear dentures to avoid continuity issues.
In 2004, Prisoner of Azkaban was released, part three of the Harry Potter film series. Watson was appreciative of the more assertive role Hermione played in this film. Among others, she enjoyed the scene where Watson's character punches Harry Potter's nemesis Draco Malfoy (played by Tom Felton) when he taunts her and also angrily storms out of class when she becomes frustrated with Divination professor Sybill Trelawney, played by Emma Thompson. She thought that Emma Thompson as Trelawney was "absolutely hilarious." Watson stated that she found comfort in the fact that many of the crew who had filmed Philosopher's Stone were also filming Prisoner of Azkaban. Then 14 years old, she stated that even for stars like fellow Harry Potter actor Daniel Radcliffe and her, teenage years were just as difficult as for anyone. Later that year, Watson also served on a panel, along with Pierce Brosnan, Chamber of Secrets co-star Kenneth Branagh, and Samantha Morton, to select the 2004 teen-aged filmmakers' "First Light" for the Film Award ceremony in Leicester Square in London.
Goblet of Fire was the fourth installment of the Harry Potter film series, released in 2005. Watson again reprised her role as Hermione Granger. Watson called director Mike Newell "fantastic," and quickly shot down rumours that she and her colleagues Radcliffe and Grint could be replaced in the following movies. For Watson, much of the humour of the film sprung from the tension between the characters Harry, Ron, and Hermione as they mature. She said: "I loved all the arguing... I think it's much more realistic that they would argue and that there would be problems. So I thought it was great fun. And it makes for a lot of humorous relief from this quite dark book." In addition, she revealed that she was a Ron and Hermione shipper, stating "Hermione and Ron just need to get it together! It just needs to happen and they just need to get on with it." Later that year, Watson became the youngest person to appear on the cover of Teen Vogue magazine, until the subsequent appearance of American actress Willa Holland. In 2006, Watson also played Hermione in The Queen's Handbag, a special mini-episode of Harry Potter in celebration of Queen Elizabeth II's 80th birthday.
In the 2007 film Order of the Phoenix, Watson reprised her role as Hermione for the fifth time in seven years. She was appreciative of director David Yates, saying he was "quiet, very calm, very thoughtful, very sensitive." She also said that one of the favourite scenes of the film was when her character practices combat magic with Rupert Grint's character Ron Weasley; when he patronises her, her spell blows him into a wall. Watson stated, "It was a real 'girl power' moment, of which there are many in this film." She was impressed with newcomers Evanna Lynch and Imelda Staunton, who played Luna Lovegood and the villainous Dolores Umbridge respectively, and also reinforced the notion that her character Hermione should romance Ron Weasley. Watson stated that she was a target of some friendly ridicule on set, because of her straight-A GCSE exam results, and added that the end scene unnerved her, when there are many flashbacks of earlier Harry Potter movies. Of the flashbacks, Watson stated, "It's just like having your baby pictures blown up on a 20-foot screen and placed in 37 countries... You see yourself and you say, 'God, who is that girl?'."
In 2007, Helen Barlow of The Sydney Morning Herald said that Watson was no longer perceived as a child actor, but as a sensual young woman who dressed up and appeared on newspaper covers. Watson herself toned down this impression, stating "I love dressing up, but it doesn't rule or dictate my life." Additionally, she was voted number 98 in the FHM 100 Sexiest Women in the World 2007 list. Watson herself said this was "the weirdest thing ever... I was like, 'Good God!' But I suppose it is a compliment for me and Hermione."
Watson's work in the Harry Potter series has amassed her a combined £10 million ($20.3 million). Watson herself acknowledged that she will never have to work again for money, but she has declined quitting school and becoming a full-time actress because "learning keeps [her] motivated."
On July 9, 2007, Watson and fellow Harry Potter co-stars Daniel Radcliffe and Rupert Grint left imprints of their hands, feet, and wands in front of Grauman's Chinese Theater in Hollywood.