Daniels said Carrey approached directors Peter and Bobby Farrelly two years ago about doing a sequel.
"Jim has been against all sequels, and you know, understandably so. ... But he turned 50 and that will mellow you out, and suddenly he's going, 'Let's have some fun. ... Come on,' and we're going, 'Great,' and so the Farrellys said, 'This isn't a money grab. Let's really write a great second movie that takes the original and then blows it up even further, and so I think they did that," Daniels said in an interview Wednesday.
Universal Pictures, which acquired the domestic distribution rights after Warner Bros. dropped out, confirmed the sequel.
"It's taken two years to get the studios and all that stuff worked out," Daniels said. "The easiest thing to say in Hollywood is 'no.' You keep your job if you say 'no.' If you say 'yes' and you're not right, you lose your job. There's a lot of 'no.' And we had a lot of 'no' for two years and finally 'yes,' it's comin' around, and I think it's got a chance to be I hope better than the first one."
Daniels said he's read the script and calls it "painfully funny."
The original premise wasn't that deep. It followed two well-meaning but moronic friends, Lloyd Christmas (Carrey) and Harry Dunne (Daniels), as they traveled cross-country to find the owner of a briefcase filled with money.
"We're middle-aged and still that stupid. Our IQ has not gone up one point combined," he said. "So it's a frightening thing. You're gonna see the two of us standing there trying to put thoughts together and you want to put underneath, 'Kids don't do this at home.' It's that stupid."
Daniels, 58, is known for his critically acclaimed roles in "The Squid and the Whale" and "The Purple Rose of Cairo."
He stars as a cable news anchor in the HBO series "The Newsroom," which returns for its second season on July 14.
Daniels said he's always surprised by the people who approach him about his "Dumb" role.
"To have what you would think (would) be very smart, intelligent people come up to you (and say), 'Can I talk to you for a second? Don't tell anybody but 'Dumb and Dumber' (is) unbelievable.' I get that a lot."