The TG4 presenter will interview 31 Roses over two nights at the 52nd festival in Tralee in August.
He replaces Ray D’Arcy who hosted the event for the last five years.
The Rose of Tralee International Selection will be broadcast from the Festival Dome on Monday, 23 and Tuesday, 24 August on RTÉ One.
Last year, 885,000 viewers tuned in to see Charmaine Kenny crowned 51st Rose of Tralee.
Of the announcement Dáithí said: “It’s a huge honour for me to be chosen to host the Rose of Tralee. It’s a show I’ve watched all my life and a festival I’ve worked with for a good few years.
“Last year, I had the pleasure of being the chair of the judging panel, so to return this year as the presenter will be a different and exciting experience. Of course being the first Kerryman to host the show brings its own pressures, but I’m really looking forward to it.
“Some of the greats of Irish broadcasting have presented before me so I have huge shoes to fill but I hope I can do the festival and the county proud.”
Dáithí is currently in Canada and the US for seven weeks filming a new series for TG4.
Anthony O’Gara, managing director of the festival, said: “We are thrilled to have Dáithí on board as the new presenter. Dáithí has been very supportive of the festival down through the years... He has hosted the Kerry event, attended international centre selections and last year chaired the international selection judging panel.
“Ray has been a wonderful presenter of the televised festival selection over the past five years and we believe that Dáithi will be equally skilled and effective in the role. And he’s from Kerry: What more could we ask for?”
Eddie Doyle, commissioning editor for entertainment, RTÉ television, said: “The Rose of Tralee has a perennial appeal – not only for attendees at the event but also for the viewing public at home, who tune in in their hundreds of thousands. It features every year in the Top 10 most-watched programmes on this island.
“The best of broadcasters have presented this uniquely-Irish event: Gay Byrne, Ryan Tubridy, Marty Whelan, Derek Davis and Ray Darcy.
“In Dáithi, I think we have a presenter who will fit into such company with ease.”
The Irish Regional Finals take place in the Portlaoise Heritage Hotel this June Bank Holiday weekend from June 3 to 6.