Growing genetically modified (GM) food has been banned in the Lake District.
GM crops will not be grown in the park
The rejection, by the Lake District National Park Authority (LDNPA), means GM crops and organisms will not be allowed to be grown in the park or on authority-controlled land.
The decision also means they can adopt a GM free policy for services such as school meals.
The move has been welcomed by Friends of the Earth, which started a "GM free Britain" campaign last year to highlight levels of local authority opposition to GM crops.
Members of the LDNPA's implementation committee used a little-known section of European law to bring in the ban on Tuesday.
Article 19 of the 'EU GMO deliberate release directive' allows areas to be designated GM Free.
The committee's chairman, Robin Yates, had warned while it would be easy to overturn a ban, it could be impossible to reverse a decision to allow GM foods in the national park area.
South Lakeland Friends of the Earth GM campaigner Marianne Bennett said: "We are delighted that the Lake District National Park has taken this issue so seriously.
"The authority has a clear duty to safeguard the park's environment.
"GM crops pose a real threat to wildlife as well as farmers, such as organic producers who want to keep their crops GM free.
"By voting for a precautionary approach, the Lake District National Park has shown it wants to protect our environment and farming from GM pollution now and in the future."
Friends of the Earth's GM campaigner Clare Oxborrow said: "This is a fantastic result and a first for National Parks. We very much hope that others will now follow suit.
"This is more evidence that people do not want their food, farming and environment contaminated with GM pollution and another reason why the Government must refuse to allow GM crops to be commercially grown in the UK."