The 34-year-old actor - who replaced Charlie Sheen after he was sacked from the show - has reportedly signed a new one-year deal which will see him reprise his role as lonely millionaire Walden Schmidt, with co-stars Jon Cryer and Angus T Jones also returning.
Ashton will remain on $700 000 per episode but he and his co-stars have been promised a signing on bonus, according to Deadline.
It is unclear if the new season - the show's 10th - will be its last.
Earlier this year Ashton revealed he would be happy to return for a new series.
He said: "I'm having a lot of fun doing the show, working with these guys and would be interested in coming back.
"The deal that we structured for the show is kind of a test deal, 'Can we get the show up? Can we get it going?'
"The show is outperforming the numbers from before I was here, and so I think people are responding to it, and, for me having a show that people like and people want more of, that'll dictate my decision."
'Winning the lottery'
The first episode of Two and a Half Men in which Ashton appeared set a ratings record for the show, drawing in some 27.7 million viewers - more than double the number who watched the first episode of season eight in 2010.
Ashton has previously admitted landing the role felt like "winning the lottery".
He said: "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 show business, and I am ecstatic about that."