The world number nine, who started on the 10th tee, collected birdies on the 11th, 12th and 14th holes and was equally impressive after the turn, with the sole blemish to his card arriving on the second during a run of three birdies in five holes.
“It was almost a perfect round of golf, especially once the weather came in, just a lovely round,” said MacIntyre, 29.
“It’s difficult when it gets this windy. It’s hard to hit the ball good with the wind.
“So I was having to try to fight the wind on certain holes and wasn’t comfortable – but I made some beautiful shots.”
Meanwhile, England’s Nathan Kimsey made nine successive birdies at the Old Course to write his name into the DP World Tour record books, becoming only the third player to achieve the feat after Matt Wallace two years ago and Australian James Nitties in 2019.
The 32-year-old, who ended the day on five under after a 68, started his stunning streak on the second hole after a par at the first.
Almost a third of the 168-man field will complete their second rounds from 08:00 BST on Saturday, with the third round scheduled to get under way at 12:30 with a shotgun start.
With a total prize fund of $5m (£3.7m), the first prize for winning the professional event is $800,000 (£594,000), while the team championship, which has attracted a host of stars from other sports as well as from television and films, offers a $50,000 (£37,000) cheque to the winning pair.