GM, which filed for bankruptcy on Monday, said the sale was is set to close by the third quarter of this year and should secure more than 3,000 jobs in manufacturing, engineering and at Hummer dealerships around the United States.
The transaction includes plans by the unnamed investor to aggressively fund future Hummer product programs, according to the automaker.
Under the proposed deal, Hummer will continue to contract vehicle manufacturing and business services from GM during a defined transitional time period.
Also, GM's Shreveport Assembly plant would continue to contract assemble the H3 and H3T through at least 2010.
GM did not reveal other details of the sale.
The automaker has been reviewing options for the past year for the gas-guzzling brand.
GM sold about 27,485 Hummers in the United States in 2008, down 51 percent from a year earlier. Hummer SUVs starts at roughly $31,000 and go up to nearly $72,000 with options.
In early April, sources told Reuters that three bidders were in the running for Hummer, and that none of the bidders are automakers.
One bidder is from the United States and the other two are from overseas, the sources had said, adding that the bidders include private equity and wealthy individuals.
(Reporting by Poornima Gupta and Chris Kaufman; Editing by Lisa Von Ahn)