Blyth Valley district council voted almost unanimously to reject the proposed school as a major round of public consultation ended - giving their support to residents who have signed a petition.
Teachers, unions and other members of the Blyth Campaign Against Academies are hailing their success in supporting the existing school in the town, which they say will suffer if an academy is built.
Opponents also believe an academy will create tensions in the town between pupils at different schools.
But the proposed sponsor, the Emmanuel Schools Foundation which is headed by Sir Peter Vardy, claims the consultation has cleared up confusion and generated support for the project.
The education charity was invited to be the academy sponsor by Northumberland county council, which wants to change the town's education system from three-tier to two-tier. Closing Blyth's middle schools will create the need for a new secondary school, the county council said.
But plans for a pound;25million school have been met with widespread opposition from the district council and MP Ronnie Campbell, who raised the issue last week with schools minister Jim Knight.
Instead of an academy, campaigners want Blyth community college to be extended to cope with the extra pupils. They predict this will cost only Pounds 5million.
Critics have also raised concerns about the strict Christian ethos in Sir Peter's two existing academies and city technology college.
Geoff Holmes of the northeast branch of the NASUWT, who has been a leading opponent, said: "A few parents have said they want an academy but many, many more are against it. There is no need for it and it would be a waste of public money."
Sir Peter Vardy said: "Clearly there are some dissenting voices and people will continue to have questions, which we are happy to answer."