But Character Coalition chairwoman Sally Hughes said the decision meant "thousands of homeowners have been denied a say in what happens to the streets they live in".
"While we accept the judge's decision, we are very disappointed with the outcome," Hughes said.
"We do not feel that the 29,000 homeowners, on whose behalf we made the appeal, have had an opportunity to be heard.
"It will now be death by a thousand cuts as developers move in over time, and destroy the character of some of Auckland's most beautiful streets."
The coalition and other groups appealed against the provisions because they were introduced by the independent hearings panel towards the end of the process of considering the unitary plan, and were not signalled in earlier drafts of the plan.
But the Court found that the panel acted lawfully in all test cases it considered except for two minor issues relating to a viewshaft in the Strand, Parnell, and the rezoning of a property in Takanini School Road.
Hughes said the Court's decision meant that the last-minute move by the Auckland Council to change the zoning of many streets that were single-house zones in the unitary plan to multi-level dwellings would now stand.
"The fact that these zone changes were done at the 11th hour and most of the 29,000 homeowners had no idea they were happening and had no opportunity to raise their concerns is appalling. It may have been legal but, in our view, it was morally wrong," Hughes said.
"We believe the council reacted to the massive pressure it was under from the development lobby and denied 29,000 ratepayers any form of natural justice."
She rejected claims that the rezoning was required to solve Auckland's housing crisis.
"The land in many of these streets is so valuable that what we are now seeing is wealthy people buy old villas and demolish them and build bigger houses but many of these new houses are not in character with the area and still do nothing to solve the housing crisis," she said.
"Shortage of builders, cost of materials, consent delays and financing issues are all currently bigger problems than the zoning of streets which give Auckland its unique character."
She said the coalition would now look for other ways to strengthen Auckland's heritage.
"We have no intention of giving up on Auckland's heritage and character," Hughes said.
"We hope more people who care about the beauty of Auckland will join us to carry on the fight."
Auckland Council's Director Legal and Risk Katherine Anderson said: "As the decision has implications for appeals that are still before the courts, the council will not be making any further comment at this stage."
Leroy Beckett of Generation Zero, which campaigned for intensification, welcomed the Court decision.
"I'm glad we have the unitary plan now," he said. "I think everyone was acting on the basis that it was not going to be stopped, and now we can get on with fixing all the other problems."
Generation Zero only ever saw relaxing the planning rules as one of the policies required to tackle Auckland's housing crisis, Beckett said.
"Now we have to get on with building the houses, and we need to increase the number of trained builders, and we need to deal with social housing," he said.
"We still have a huge housing deficit. This just allows us to solve a small part of the problem."
