Eric Watson has bought out Sir Owen Glenn's half share in the Vodafone Warriors.
This makes Mr Watson -- who bought a stake in the club in December 2000 -- sole owner for the first time.
Sir Owen, who has said that he had invested about $6 million in the club, claimed that after the relationship soured he was offered $1 for his share. Mr Watson described that as "rubbish" but would not reveal what he paid.
Sir Owen, a billionaire philanthropist who made his fortune in international logistics, announced in May that he would transfer his stake to the Sir Owen Glenn Warriors Trust which would aim to grow the game at grassroots. The move meant his shareholding was no longer for sale and that he was making a long-term commitment to the club, he said at the time.
But Mr Watson told the Herald from London that he had bought out his former partner via the entity that had always held Sir Owen's shares and did not think the proposed trust operated.
"I believe he committed to put, effectively, the value of the proceeds of his shareholding ... into grassroots rugby league, and that's a good thing for the sport," Mr Watson said. "One would assume he would [still] inject the value into that trust except it would now be cash."
Sir Owen also pledged to put $100,000 into a nationwide survey of the sport's health and to deliver a blueprint for its future.
The feud between the two wealthy businessmen has been a distraction for the club.
The pair are embroiled in a court battle in the British Virgin Islands over other business ventures with -- according to a court ruling -- tens of millions of dollars worth of English property and more than $200 million in a Jersey bank account at stake. Mr Watson would not discuss the case other than to say it was likely to take years to sort out.
Publicity about their dispute had not helped the Warriors.
"That put pressure on the organisation, including the players and can effect the culture."
Being the sole shareholder would make decision-making simpler, he said. "I'm very pleased. I'd just like to get some runs on the board. I'd like us to be performing in the top four frequently. We still haven't delivered and I'm quite frustrated about that but we are in pretty good shape."
The club had stable management and he held high hopes for its coaching team and swathe of player recruits.
"Business partnerships either work out well, or not. Owen had a lot of good ideas. His heart's in the right place. You can see as a philanthropist he's very generous and has added value to a number of areas in New Zealand sport and education. I think he's preferring to focus in that area and made a decision to no longer be an owner."
Mr Watson wanted Mt Smart Stadium to continue to be the Warriors' home despite an Auckland Council proposal that the club move to North Harbour Stadium. "We've made our position clear that we don't want to leave Mt Smart Stadium after our lease expires at the end of the 2018 season. We don't believe that is the solution at all."
Mr Watson's passion for the game came from growing up in Christchurch. "I played very poorly for Addington Rugby League. It's in the blood for any working-class boy in Christchurch, or New Zealand for that matter."
He admits to thinking that winning the NRL title as an owner was going to be easy when the Warriors made the Grand Final in just his second season with the club. Although the franchise is still young at 20 years, that is a summit the organisation is yet to conquer.
His predictions for 2016? "I don't want to jinx it [but] I think we'll go close to winning the [NRL Auckland] Nines and I'm hoping we get one of the home [NRL] finals games."