The investors, Filmyard, includes construction magnate Ron Tutor and investment firm Colony Capital.
Disney has been negotiating with potential buyers for months to sell the division, which has made films such as Pulp Fiction and Shakespeare in Love.
Earlier this week, Disney bought the social gaming developer Playdom.
"Although we are very proud of Miramax's many accomplishments, our current strategy for Walt Disney Studios is to focus on the development of great motion pictures under the Disney, Pixar and Marvel brands," Disney's chief executive Robert Iger said.
Disney wants to concentrate on these family-orientated divisions, which produce popular films such as Toy Story, that also come with highly profitable merchandising opportunities.
"Disney has been very smart with its film strategy," media analyst Theresa Wise told BBC World Business Report.
"One of the big issues with movies is very few films break even... so they need other revenues. Disney has the fantastic ability to sell family films and all the merchandise that goes with it.
Disney has owned Miramax since 1993 when it bought the firm from Hollywood heavyweights Harvey and Bob Weinstein.
The Weinstein brothers, who recently attempted to buy it back from Disney, named the film company after their parents Miriam and Max.
Entertainment giant Walt Disney has announced the sale of its Miramax film division for about $660m to a group of private equity investors.