The 61-year-old had been tipped to reprise his role on the 11th series of the show but had yet to officially confirm the news until his appearance on Irish radio presenter Colm Hayes's 2FM show.
"I knew I was doing the show but I just signed the deal and I'm very happy with it," Louis told the Colm "At my age you have to keep working!"
Louis had previously said he was keen to join Simon Cowell and Cheryl Cole on the judging panel, and music mogul Simon seemed equally enthusiastic.
"I would love Louis to come back and do the show, it wouldn't be the same without him," said Simon. "Other people have different views, so we have to agree on it."
While Louis, Simon and Cheryl are all confirmed, fans of the talent show are still guessing who the fourth judge will be, with Spice Girl Mel B as the frontrunner.
Louis hinted Mel B might be the fourth judge
"It has to be someone I like," joked Louis. "I'd love it to be Sharon Osbourne, but I don't think it's going to be her. There are all sorts of rumours going around.
X Factor 2014: 20 stars rumoured to take fourth judging spot
"I think it could be Mel B from the Spice Girls," he added. "I love her and she's quite mad. She also did both the American version and the Australian versions of X Factor."