The game had originally been scheduled for last summer, but several of the players due to be involved had commitments revolving around the European Championship in France, meaning the fixture had to be called off.
There will also be a return leg between the two sides, which will take place at Old Trafford on Sept. 2.
Managed by Jose Mari Bakero, Barca legends played their first ever game earlier this year in Querertaro against a team which included former Mexican stars.
Among the players to play for the Blaugrana that day were Hristo Stoichkov, Vitor Baia, Edmilson, Gheorghe Popescu, Ronald de Boer and Gaizka Mendieta.
Since that game in April, Ronaldinho has returned to Barca in an ambassador role and upon his appointment the club also said he would be involved with the legends side, although no players have been confirmed for the match against United.
Barca say they will announce further fixtures soon as they bid “to honour the many footballers that have worn the club jersey over the years and to help globalise the Barca name and values through former players.”
Manchester United legends, meanwhile, will play an all-star charity match at the nib Stadium in Perth in March.
Former United players, including Paul Scholes, Dwight Yorke, Denis Irwin and Mikael Silvestre, will take on the PFA Aussie Legends in a clash that will raise money for the Manchester United Foundation and the DT38 Foundation.