In 1986, he began appearing in ITV's popular Saturday morning children's series, No. 73. But shortly afterwards, he switched to the BBC to launch another Saturday morning children's series, On the Waterfront, alongside fellow ex-No. 73 host Kate Copstick.
In 1988 O'Connor also appeared regularly in short comedy sketches co-written by himself for the Observation round in ITV game show The Krypton Factor. In the same year he took over from Jeremy Beadle as the presenter of the daytime game show, Chain Letters. He returned to acting to play the role of the computer in early 90's children's sci-fi show Kappatoo but it was his career as a quiz-show host that took off, and he subsequently presented the UK version of Talk About, moved to Saturday night prime time in 1991 with One to Win, and returned to daytime television with The Alphabet Game. This latter show was devised and produced by O'Connor, having formed his production company, Objective.
This marked the turning point in his career, and although O'Connor has made numerous on-screen appearances since then, he has mainly been working behind the camera. He has produced numerous comedy and magic related television shows, perhaps the most notable being the critically acclaimed sitcom, Peep Show, and most of Derren Brown's programmes.
In 1994 O'Connor hosted & presented an ITV & Family Channel Game Show called Family Catchphrase, which was a spin off from Catchphrase, from 1994 until 1997, when O'Connor left & once again moved back to a daytime slot after the show and spin off ran for about 4 and a half series.
In 1996, a year before leaving Family Catchphrase, he established Objective Productions with Michael Vine. O'Connor holds the position of Chief Executive.