Hayson had reportedly deposited more than A$700,00 in O'Sullivan's TAB account during several years and was part of a police investigation into betting patterns on several NRL matches.
Though O'Sullivan was never implicated in any wrongdoing, his close association with Hayson saw the NRL cancel his registration indefinitely.
O'Sullivan was also at the Melbourne Storm during their salary cap scandal, although he never faced any sanctions.
Warriors chief executive Cameron George denies luring O'Sullivan across the Tasman is a risky move.
"I've had numerous chats with Peter and my due diligence delved into what happened with the NRL," George said.
"The NRL feel the same as me. It's in the past and we move on. Rugby league is full of redemption stories and we can be part of that as well.
"There is no risk in my mind at all. What's happened in the past has been dealt with and the NRL has said he is welcome back into the game."
According to George, O'Sullivan is the final piece in the Warriors' management jigsaw.
"He gave an outstanding presentation, with his vision for the club and the talent around our roster," he said.
"The club has never had this much experience or people involved who are so good at their game."
The Warriors have been talking with O'Sullivan for a few months, although the final negotiations were put on hold until the club's ownership was resolved.
His contract still needs to be registered with the NRL but that is expected to be a formality.
Warriors coach Stephen Kearney yesterday revealed he had played a major role in luring O'Sullivan to Mt Smart Stadium.
"I thought that was an area where we could really improve, and through my connection with him and relationship with him, I thought he would be the best person for that role," Kearney said.
"He is one of the best I have seen, not only with shaping your NRL list [but] in everything underneath it as well."
According to Kearney, O'Sullivan is a football obsessive.
"That is what he lives for," said Kearney. "He watches footy all day: schoolboy footy, carnivals, reserve grade, whatever. And he has a great eye for talent. He's not perfect - not everyone is going to come through - but he's very good."