[2] On 9 June 2010, he co-hosted the opening ceremony of the 2011 Special Olympics World Summer Games Irish heats at Thomond Park with Des Cahill.
He picked up where Marty Whelan had left off, engaging the audience with his natural personality, a world apart from the 'jocks' that stalked the Radio Centre in Montrose at the time.
Noted for his choice of brightly coloured jumpers, Dempsey presented The Den until the summer of 1990 and later reflected on his time at the helm in a 2008 RTÉ documentary.
He left RTÉ for Today FM in July 1998 and since 21 September 1998 (when his breakfast show was launched) he has worked at the station with his Gift Grub team providing comedic value.
Attempts have included Hector Ó hEochagáin, Ryan Tubridy, Colm Hayes and Marty Whelan in recent years.
Dempsey appeared on The Restaurant where he bamboozled the critics with his Mini Bloody Mary Burgers, JFK's Lidded Lobster Soup, Swedish Meatballs, Tagliatelle with Lightly Curried Prawns, Deeply Bitter Chocolate Mousse and a dish he called "The Bomb".
[8][9] In late August 2015, Dempsey and Today FM colleague Louise Duffy presented The Seven O’Clock Show on TV3 filling in for usual hosts Martin King and Lucy Kennedy.