The recording wizard has engineered two songs on the Beatles legend's upcoming album - the title track New and another number, named Alligator.
MCCartney was first attracted to the idea of working with Ronson when he entertained the congregation by DJing at the Fab Four star's wedding to Nancy Shevell in 2011, but the deal was not agreed until they met again in the restroom at a New York restaurant.
MCCartney tells NME magazine, "That sounds pervy, doesn't it? We bumped into each other and said, 'Hi, we should work together.' So I called him to ask properly and he said yes."