The actor - who was a fan of the first, Matthew Vaughn-directed outing - will play Colonel Stars in the comic book movie sequel, reports Deadline.
Carrey had been rumoured for the role last month. Director Jeff Wadlow hinted that he had joined the cast earlier in the week.
Colonel Stars is a member of the crimefighting team Justice Forever that is introduced in Mark Millar and John Romita Jr's follow-up comic book series.
Aaron Taylor-Johnson, Chloë Moretz, Christopher Mintz-Plasse and Nicolas Cage will reprise their original roles for the sequel.
Lyndsy Fonseca, Yancy Butler, Donald Faison, John Leguizamo, Lindy Booth and Andy Nyman have also joined the cast.
Kick-Ass 2 will be released on June 28, 2013 in the US and on July 19, 2013 in the UK.
Watch the trailer for Matthew Vaughn's original Kick-Ass film below: