The duo played together at the Medinah Country Club two years ago, where they defeated combinations of Luke Donald/Sergio Garcia and Lee Westwood/Donald in the foursomes, as well as getting the better of Rory McIlroy/Graeme McDowell in the fourball.
Speaking to reporters this afternoon, five-time Major winner Mickelson confirmed that the pair will resume their association at Gleneagles.
"I've got a good partner. Obviously I'm going to play a game with Keegan. I don't think I'm letting go of any secrets here. If you've noticed, we've played together these first few [practice] rounds. We seem to have a good partnership and he seems to bring out some of my best golf," said the 44-year-old.
Mickelson will be featuring at the event for the 10th time in his career.