The Prosper Northland Charitable Trust said the centre would spur $40m in visitor spending in the first five years.
It had taken over the conference centre project, and would own the finished product.
The trust's revised design provided to council had 850 seats and a 40 per cent smaller floor area. Theatre capacity was removed and the building height was reduced.
Trustee Ian Reeves told RNZ the centre was also still expected to stimulate other builds nearby, including a 4-star hotel "which is very necessary - and has been acknowledged for years and years as necessary - and also further apartment developments".
More than 5000 people submitted their views on the proposals last year - nearly 80 per cent were against the old proposals.
When the council rejected the project, Whangārei MP Emily Henderson said she was "very disappointed".
Northlander and former deputy prime minister Winston Peters told RNZ the city was looking "a gift horse in the mouth".
Government funding of $59m for the build was about to go back into the Crown Infrastructure Partners' pool, but Ōruku campaigners asked for the money to stay ringfenced while they revised the plans. They have now retained the allocation.
Councillor Vince Cocurullo complimented their stickability.
"They have kept it alive, they have kept the communications going," he said.
"We all thought the project was completely dead. We thought the Government had turned around and said 'right this council, the Whangārei District Council doesn't want it, therefore it's not going to happen'."
But the councillors' vote was not unanimous.
Tricia Cutforth chose to abstain, and Simon Reid (Ngāpuhi) was against, and said it was unfair for some building projects to have infrastructure costs cut, and others not.
"Our ratepayers have clearly told me - well the ones that have contacted me - that they have not had any help in a development."