The English trio of United, local rivals Manchester City and Liverpool will join Real and Milan plus AS Roma, Inter Milan and Olympiacos Piraeus in the Guinness International Cup, which takes place from July 26-August. 4.
"Year one of the Guinness International Champions Cup set the new gold standard for soccer in the United States," Charlie Stillitano, Relevent Sports CEO, said at the tournament launch in Miami.
"Our only goal was to provide fans with the best football experience in their own backyards. We look forward to building on these successes in 2014."
The eight teams, who account for 150 domestic titles, 88 domestic cups and 27 European Cup/Champions League trophies, will be divided into two groups of four with the winners of Group A and Group B meeting in the final.
The showpiece match will be played at Miami's Sun Life Stadium on August 4. There will also be matches in Charlotte, Chicago, Dallas, Denver, New York/New Jersey, Philadelphia, Phoenix, Washington DC and two additional cities.
The participation of the English Premier League teams depends on games not affecting any European qualifying matches.