A company owned by businessman Denis O'Brien has purchased Today FM, FM104 and Donegal's Highland Radio from Emap.
An Emap statement to the London Stock Exchange said that Mr O'Brien's Communicorp paid £135m (€200m) for the three stations.
London based Emap, the publisher of Closer and Grazia magazine, decided to sell its radio stations in Ireland some months ago so it could concentrate on digital media.
Among the bidders for the stations were The Irish Times, TV3, a group involving businessman Ulick McEvaddy, UTV and Scottish company New Wave Media.
There are immediately competition issues for Mr O'Brien as his company already owns Newstalk, 98FM and SpinFM, and the takeover has to receive approval from the Competition Authority and the Broadcasting Commission of Ireland.
Speaking on RTÉ Radio, Emap's Regional Manager Willie O'Reilly said meetings with the Competition Authority will begin next week.
'The sale is conditional upon obtaining certain necessary regulatory clearances which are expected to be obtained in the second half of our financial year', Emap's statement said today.
Emap acquired the three stations with Scottish Radio Holdings (SRH) in 2005.
In the year to 31 March, the business had revenue of £21m and operating profit of £7m.
The sale is expected to be tax free for Emap with the proceeds used to pay off the group's debt.