Bristol Airport's expansion plan, which it said would boost its passenger capacity by two million a year, has been rejected by councillors.
Ten million people a year can travel from the airport and bosses wanted to build a new car park and transport hub to boost that to 12 million.
Bristol Airport said the expansion would stop millions of people from the region driving to London airports.
But North Somerset councillors said it would be harmful to the environment.
Passenger numbers at the airport are currently 8.9m a year but it has a capacity of 10m.
The application had about 8,800 objections from members of the public and 2,400 messages of support.
Councillors voted 18-7, with one abstention, to reject it.
Bristol Airport chief executive Dave Lees said the decision risked "putting the brakes" on the future growth of the region.
He said they would reflect and consider whether to appeal or submit fresh plans.
At the four-hour meeting in Weston-super-Mare, councillors spoke out against the plan which had been recommended for approval by planning officers.
Councillor John Ley-Morgan said: "How can we achieve our ambition for carbon neutrality by 2030 if we approve this decision?"
Supporting the application, Unite representative Mark Hutchison said the expansion would create thousands of jobs and bring a huge boost to the economy.
But Ciaran Cronnelly said that while he supported economic growth, it should not at "any cost".
Other prominent people have also expressed concerns about the expansion including local MP Liam Fox and Bristol band Massive Attack.