He's the show's fourth permanent presenter.
A former RTÉ employee says the live element of the Late Late Show will be the most interesting aspect to watch, ahead of Patrick Kielty's debut.
The Down star will sit in the hot seat for the first time tonight, replacing Ryan Tubridy, whose 14-year run ended in May.
The show, which was first broadcast in July 1962, will be shortened to 90 minutes.
Former RTÉ Midlands Correspondent, Ciaran Mullooly, says it's going to be a different programme:
Mr. Kielty will be the show's fourth permanent presenter.
Speaking ahead of tonight, he says he's really looking forward to it: