The Countryside Agency has agreed the boundary for the South Downs national park.
Following months of consultation, the body has made 60 changes to the park's boundaries, which will cover large parts of Sussex and Hampshire.
The most significant in Sussex are the inclusion of Ditchling and Coney Hill at Westdene.
The map of the final boundary will form part of the designation order which will create the new national park.
John Carden, of the South Downs Campaign, said: "The majority of people wanted a national park and this is what the agency has agreed."
Brighton and Hove City Council leader Ken Bodfish said: "We are the only council to have supported steadfastly the principle of a national park.
"We are a stage closer now and this is really good news for our city."
Open spaces councillor Heather James said: "This is a day which we have all been waiting for."
The agency says designation as a national park is the best way to protect the Downs, provide proper management and create opportunities for people to enjoy the countryside.
The South Downs National Park Designation Order will be published in January for one month to allow representations or objections to Secretary of State Margaret Beckett.
Revocation orders will be made for the East Hampshire and Sussex Downs Areas of Outstanding Natural Beauty, which lie largely within the national park boundary.
Agency chairman Ewen Cameron said: "This is an important decision for the South Downs, for those who live and work there, and for everybody who cares about this special part of the country."
He added: "We are aware, however, that a number of local authorities have already indicated that they will oppose the designation. If this is the case, there will be a public inquiry.
"We are confident the decisions we have made today are right and we will defend them if necessary."
The Sussex Downs Conservation Board, which runs the Downs now, said the continuing debate could result in a period of inertia.
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