He hosted the original pilot series of the American version of Deal or No Deal for ABC in early 2004.
Other participants included Nelson Mandela, Mohammed Ali, and U2.
In 2006, he hosted a segment on ITV's coverage of The Prince's Trust 30th Birthday LIVE alongside Kate Thornton.
In 1997 he set up the Belfast-based TV production company Green Inc with TV director Stephen Stewart, making shows such as The Afternoon Show, Patrick Kielty Almost Live, and Ask Rhod Gilbert.
It was reported in 2010 that Kielty had sold his share in the company.
Kielty graduated to presenting programmes such as Last Chance Lottery and Patrick Kielty Almost Live, broadcast throughout the UK.
Alcoholic former football star George Best later gave his first TV interview following his liver transplant to Kielty on the same show. He did an impersonation of Martin Mc Guinness (who bears a slight resemblance to Art Garfunkel) singing the Simon and Garfunkel song, "Bridge over Troubled Water".In 2016 Kielty returned to BBC Northern Ireland to present programmes, including the comedy panel game show Bad Language alongside Susan Calman and Paul Sinha.He then hosted television documentary Patrick Kielty's Mulholland Drive which focused on the life of William Mullholland and the California Water Wars.In 2006, Kielty returned to the stand-up scene with a brand new UK tour.A DVD, filmed at Belfast's Grand Opera House, was later released.John Kielty was to have been a key witness in ITV Central's defence of a libel action brought by Jim Craig, who was suing the television company over a broadcast of The Cook Report which connected him to racketeering, and is said to have ordered John Kielty's murder.