The city will seek to rezone 47 acres at Coney Island with the idea of creating a modern, year-round amusement district surrounded by thousands of units of new housing, Mayor Bloomberg announced yesterday.

“When people around the nation hear the words ‘Coney Island,’ they think of fun in the sun, of beaches, boardwalks, and bumper cars on the Brooklyn shoreline,” Mr. Bloomberg said yesterday morning in front of the Brooklyn Chamber of Commerce.

“But we all recognize that Coney Island just isn’t what it could be,” he added.

The mayor’s plan, which he said could bring in $2.5 billion in private investment over the next decade, includes rezoning the area for 4,500 residential units, some slated to be “affordable” housing, and 460,000 square feet of retail space.

Mr. Bloomberg said the city would remap 15 acres to create new city parkland along Coney East, which would expand the amusement area and allow new rides, restaurants, and attractions, with the goal of bringing visitors to the area year-round. The management of the amusement park would be leased to an outside developer, Mr. Bloomberg said.

The city will begin the public review and approval process of the rezoning plan early next year.

Mr. Bloomberg’s plan could stymie the ambitions of developer Joseph Sitt, who had planned to erect a hotel and retail stores on land now designated as an amusement district.

Mr. Sitt, the chairman of Thor Equities, said in a statement that he was disappointed by the mayor’s announcement but would continue to work with the city and community to do what they agree would be best for the neighborhood.

“We’re disappointed by the mayor’s presentation, but are optimistic that a deal can be reached between the city, the landowners, and the community to make Coney Island an even greater place to live and visit,” Mr. Sitt said.

Mr. Sitt spent $100 million to acquire 10 acres of Coney Island property, and aims to develop hotel, amusement, and retail spaces.

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