“They let me do the craziest stunt I was ever able to do,” said Radcliffe, who revealed the scene takes place in 2005’s Harry Potter and the Goblet of Fire.
He said: “It was like a 40ft fall down a roof. I was on a wire but I was properly in free fall. It was only there to catch me at the end. And I was absolutely terrified.”
The 31-year-old continued: “I worked a lot with the stunt department by then, and they were like, ‘You can do this. Do you want to try it?’ And I said yet. But then I got up there and was absolutely terrified.”
The scene Radcliffe is referring to takes place during the first task of the Triwizard Tournament.
Along with the other contestants taking part in the competition, Harry goes up against a dragon.
During the action sequence, Harry is knocked from his broom and slides down a roof that leaves him clinging to the edge of a building.
Radcliffe was only 15 years old when shooting the film, which is the fourth of the eight instalments.
Reminiscing about the moment, which he recalled they filmed “two or three times”, the actor said: “I’ve realised since that, that was very special circumstances in that set and I will never be allowed to do something like that again.”
Radcliffe currently stars in TBS’s anthology series Miracle Workers. The third season of the comedy series is set to premiere on 13 July.