The My Week with Marilyn actor, who will play Marius in the upcoming film, spoke to Digital Spy about the audition process, revealing that he had to "serenade" filmmakers in order to land the role.
Additional reporting by Tom Mansell.
"I totally had to serenade [the film's director] Tom Hooper and Nina Gold, the casting director, and Cameron Mackintosh, who's one of the producers," Redmayne said.
"It was interesting," he continued. "It was a musical my parents took me and my brothers to when I was a kid and I always enjoyed it. When it came out, I was like, 'Give it a shot'."
Redmayne, who was speaking after being nominated for the BAFTA 'Rising Star Award', added: "It's really exciting actually. It's an amazing cast they're accruing. I think it could be an interesting one."
Russell Crowe, Amanda Seyfried, Anne Hathaway, Hugh Jackman, Helena Bonham Carter and Sacha Baron Cohen are all set to star in Les Misérables, which will begin filming soon.
Redmayne recently joined the cast of BBC One's Birdsong.
Les Misérables will open in cinemas on December 7, 2012.