Radcliffe began acting at age six when he appeared as a monkey in a school play. After passing up an opportunity to audition for a television production of Charles Dickens (Dickens, Charles)'s Oliver Twist, he caught the attention of television producer Kate Harwood, who was impressed by his “charm and simplicity,” and he was cast in the title role of David Copperfield (1999). Two years later Radcliffe appeared in the film The Tailor of Panama (2001). His big break came when he was cast in the film adaptation of J.K. Rowling (Rowling, J.K.)'s Harry Potter and the Sorcerer's Stone (2001). Radcliffe played Harry Potter, a lonely orphan who discovers that he is actually a wizard and enrolls in the Hogwarts School of Witchcraft and Wizardry. The film was a box-office hit, and he reprised his title role in Harry Potter and the Chamber of Secrets (2002), Harry Potter and the Prisoner of Azkaban (2004), Harry Potter and the Goblet of Fire (2005), and Harry Potter and the Order of the Phoenix (2007).

Radcliffe's other on-screen credits include the British television movie My Boy Jack (2007) and the Australian coming-of-age film December Boys (2007). Off-screen, he starred in Peter Shaffer's Equus, which opened in London's West End in 2007. He played the challenging role of psychotically deranged teenager Alan Strang, whose unnatural love of horses drives him to blind six of them with a hoof pick.