Construction is set to begin in 2013 and is expected to be finished about three years after that.
The "Avatar" attraction is to be an immersive land spanning several acres and will cost less than half of the estimated $1 billion it cost to expand Disney California Adventure Park, or around $400 million.
CEO Bob Iger made the announcement at a news conference on Tuesday.
Cameron, who is working on the second and third installments of the top-grossing film of all time, said the attractions would be a way to bring the lush world of Pandora to life, and would include animatronics and potentially multimedia shows that use 3-D and holographic technology.
"This is a pretty darned exciting project," Cameron told reporters.
Walt Disney shares rose 30 cents to $32.81 in afternoon trading Tuesday.