The world No.2 made light work of the treacherous conditions to bag six birdies and join American Sam Burns as the early first-round clubhouse leader on Thursday (Friday AEST).
McIlroy placed the field on notice with a five-under 67 that was five shots superior to his level-par opening last year when the Northern Irish superstar finally completed the rare career grand slam with an emotion-charged play-off win over Justin Rose.
Burns was equally impressive in going bogey-free in his round of 67.
Australian Jason Day posted a steely 69 to be sitting equal third, two shots off the pace, with Americans Kurt Kitayama and 2018 champion Patrick Reed.
Reed made a lightning start with eagles on both front-nine par-5s but let it slip coming home.
In-form dual major winner Xander Schauffele and Day's playing partner Shane Lowry were among the big names a stroke further back and safely in the clubhouse at two under.
Among the afternoon starters, world No.1 Scottie Scheffler was also going well on three under after eight holes, but pre-tournament fancy Bryson DeChambeau struggled with a four-over 76.
Hours earlier, the great Jack Nicklaus joined his son Jackie, placed his ball on the tee and offered a tongue-in-cheek warning to the patrons lining the tee box - "Oh, boy, watch out, and I don't mean that facetiously!" - before proceeding to hook his ceremonial tee shot right at them to open the 90th Masters.
"I said, 'spread out on both sides because I don't want to kill anybody,'' he noted, after the ball cleared the heads of the patrons down the left side by a couple of feet.
"If it'd been a little closer I might have."
At 86, the Golden Bear, who joined his fellow greats, 76-year-old Tom Watson and 90-years-young Gary Player in the traditional launch, said he didn't really play anymore. He did once all of last year, and once more this past February.
"But it's such a nice ceremony and it's a real honour to be invited," said the 18-times major champion and six-times Masters winner.
"I hope to be able to do it as long as I cannot kill anybody."