The UK-based company, whose existing venues include Madame Tussauds and the London Dungeon, has chosen the Grapevine Mills shopping mall as the location for its latest Legoland brand extension.
Work is due to start in June 2010 and should be completed by March 2011.
It is the latest in a series of international projects launched by Merlin Entertainments Group, which is set to launch the Pepsi Globe - an attraction modelled on the London Eye - in New York next year.
There is also speculation that Merlin Entertainments Group will be floated on the stock market early next year, but a spokesman said no timescale had been set.
"It's inevitable that it will happen at some point but we are waiting for the right time," he said.