The 18-year-old was at the Odeon in Covent Garden, London, to launch the Australian film, in which he stars as Maps, the oldest of a group of orphans on a coming-of-age adventure.
Fans of the JK Rowling franchise, in which Radcliffe has played the famous boy wizard since first linking up with the film at the age of ten, lined the streets outside the cinema and greeted his arrival in raucous fashion.
Commenting on the reception, Radcliffe admitted that the apparent adulation was "mad" but said he was glad of the publicity the film was getting.
"This film needs all the help it can get – it's not like Potter, it's a very little film," he said on introducing the first showing of the picture.
In December Boys, Radcliffe's character is one of four orphans all born in December who are given a trip to the coast as a present after years in the desolate outback.
Maps is the natural leader of the group and experiences a sexual awakening with a feisty blonde named Lucy during the holiday.
Radcliffe's performance has received mixed reviews but he has already confounded many of the critics with his displays on the West End in Equus earlier this year. 
