He told UsMagazine.com: "I've never probably in my 13 years in show business received more phone calls and emails from people congratulating me on this job.
"You'd almost think I won the lottery or something, which I kind of did. I've got the best job in showbusiness, and I am ecstatic about that."
Ashton – who is married to actress Demi Moore – is thought to be set to earn around $1 million an episode for the show, but the programme's writers have released no details as to who his lead character is or how he will be introduced.
Jokingly referring to Ashton’s 6ft 2in frame, Jon – who plays Alan Harper in the show – said: "I'm incredibly happy they're bringing Ashton to the show. But the question that I have to ask is, ‘Did you have to get the tall guy? Really? Is that necessary?’ ”
Ashton later posted a photo of himself and his two new cast mates posing with mock angry faces on his twitter page, with a caption reading: "First cast argument 2.5 men. (sic)"
Exiting star Charlie – who starred in the first eight series of the show – was fired from 'Two and a Half Men' because of his hard-partying lifestyle and comments he made to Chuck, such as calling him a "sad silly fool” and a "low rent, nut-less sociopath"