The Staggies will meet the Premier League champions to open the newly-turfed and refurbished Victoria Park on July 20 following talks between director of football George Adams and former United boss Sir Alex Ferguson who worked together at Aberdeen in the 1970s.
"Thanks to an agreement between George and Sir Alex, the game will go ahead next month,” said County chairman Roy MacGregor.
"We are delighted about this and cannot wait for a Manchester United select, which could include a few first-team players, to fly up for this match.
"With the new pitch being laid this month, we didn't really want to play a match here before the start of the season, but clearly this was too much to resist. To have Manchester United be our opponents - to christen the pitch - is terrific news.
"The last time they were here, I believe, was in the 1970s, so it's fitting they are coming back now for an occasion when our new stand will be complete and pitch in place."