Big Brother: Celebrity Hijack kicked off on Channel 4 last night after the previous series sparked an international incident following the alleged racist bullying of Indian actress Shilpa Shetty.
O'Leary, who is presenting the programme for the last time, told BBC Radio 1's Newsbeat that it had been a "mistake" to axe the original format, saying: "I still think it's a good show and I don't think anyone should apologise for what happened last year. It conjured up debate and asked serious questions."
The new series, which continues on E4, sees celebrities taking on the role of Big Brother and setting tasks for twelve "young and gifted" housemates between the ages of 18 and 21.
Little Britain's Matt Lucas was the first star in the hot seat last night, giving Scottish politician John instructions during the live launch.
The show's producers have told hijackers Lucas, Jimmy Carr, Joan Rivers, Brian Sewell, Malcolm McLaren and Ian Wright that they are free to cause mayhem in the house.
Big Brother: Celebrity Hijack continues at 9pm tonight on E4.