United won the tournament last year, beating Liverpool in the final, and attracting a crowd in excess of 109,000 for their match against Real Madrid in Michigan.
As well as the two Premier League sides, Barcelona, Paris St Germain, Porto and Fiorentina will travel over from Europe for this year???s renewal of the event.
And they will be joined by Mexico???s Club America and the Major League Soccer sides LA Galaxy, New York Red Bulls and San Jose Earthquakes.
Dates have yet to be finalized for the tournament, although it is unlikely to finish as late as last year (final was on August 4) because the Premier League season gets underway on August 8.
Manchester United manager Louis van Gaal was critical of their three-week five-match summer schedule last year and has reportedly sought assurances on the Champions Cup dates.
Van Gaal is believed to want United to be away for no more than two weeks and back before August, in light of the early start to the Premier League season.
Real Madrid will not be involved this year and the Champions League holders will take part in a sister tournament in Australia, along with Manchester City.
Manchester United group managing director Richard Arnold, said: ???The club is delighted to be returning to the United States for Tour 2015, presented by Aon.
???Manchester United made history in its last visit to the United States by breaking the country???s soccer attendance record and the huge level of support for the club was evident in every city we visited.
???This summer???s tour is the latest in a long line of visits to the US, a tradition that began some 65 years ago under the guidance of the great Sir Matt Busby.
???This tour will not only provide the team with first-rate preparation for the season ahead, it will also allow many of United???s eight million US followers to get closer to the club they love.???
And Chelsea Chairman Bruce Buck said: ???I am delighted the club will take part in the International Champions Cup this summer, against top-quality opposition.
???We look forward to returning to North America for the eighth time in 12 years, and visiting some iconic venues, in which I am sure there will be strong Chelsea support.
???We know the facilities we use will be second to none and Jose (Mourinho) and the squad will be able to prepare for what already promises to be an exciting 2015/16 campaign. I am also pleased to confirm we will be continuing the important work of the Chelsea Foundation during our visit.???