Bernd Weisberger made the most of lower than predicted winds to fire a flawless 64 and take a one-shot lead into the second round, with 18 players within three shots of the Austrian.
One of those is McIlroy, whose 66 was enough to leave him six under, two off the lead, as he chases victory after finishing second in his last three events.
The world number one was returning to the scene of his first professional win six years ago, where he has secured four consecutive top-10 finishes, and showed why he is so fond of the Emirates Golf Club with seven birdies and just a single bogey on the ninth.
The wind normally poses some challenge in Dubai but still conditions led to low scoring and McIlroy, who started on the 10th, admitted he would have liked more of a test.
"I'd be disappointed if I didn't shoot anything below 68 today, especially with the conditions and 66 is a nice start," he told Sky Sports 4.
"I'd like to see it blow a little bit and make it more of a challenging golf course. You still need to hit the shots, but it would be nice to play in some conditions that are a little different than this."
He added on the European Tour website: "It was a little disappointing to bogey the last but the golf I played up until then was nice.
"It's a solid start. I felt like I hit the ball very well for the most part and gave myself plenty of birdie chances and was able to covert a few more of them than I was doing in Abu Dhabi a couple of weeks ago.
"I putted nicely and it's definitely something to build on for the next few days."
Of the other Irish, Graeme McDowell finished birdie-birdie to join the group on five under which included Kaymer, Race to Dubai leader Danny Willett and Argentina's Emiliano Grillo, who went out in 37 but came back in 30 as he birdied his last seven holes.
Damien McGrane opened his tournament with a one-under 71, and Peter Lawrie shot a one-over 73.
Elsewhere it was a mixed day for Michael Hoey and Darren Clarke. Hoey got off to a poor start with three bogeys on the front nine but four birdies and a further bogey on the 15th left him on level par.
It was a similar story for Clarke who managed to double bogey the fourth hole before and eagle on the 13th helped him to a one-over par finish.
"I'd like to see it blow a little bit and make it more of a challenging golf course" - Rory McIlroy
Back at the top of the leaderboard, Wiesberger came alive on the back nine after reaching the turn in 33, picking up a shot on 10 and then registering five consecutive birdies from 13 to set the target.
"I've always played well here," he said. "I know I can make a lot of birdies out here.
"Perfect conditions like we have had the last couple of weeks make the guys go low."
Wiesberger was one shot clear of a chasing group of four which featured Belgian Nicolas Colsaerts, American Peter Uihlein and English duo Lee Westwood and Andy Sullivan.
Sullivan claimed his first European Tour title at the South African Open earlier this year and was in sparkling form again as he recorded five birdies and an eagle on the 18th to share the lead.
The likeable 28-year-old was playing alongside McIlroy and Martin Kaymer and, while he looked perfectly at home in such company, he admitted to being a little overawed.
"It's one of the best days of my life out there today, just watching Rory and Martin go at it," he said.
"When I first looked at the draw I thought they'd messed it up. I thought 'I can't be playing with these guys'. It's an absolute pleasure.
"I didn't really look at the leaderboard today. I was just watching them guys play golf and it was just absolutely fantastic, one of the best days of my life.
"And to play the way I did as well was brilliant."
Fellow Englishman Westwood has 22 more Tour wins than Sullivan and finished with two birdies in a flawless 65.
Two-time defending champion Stephen Gallacher was alongside McIlroy on six under with the Ryder Cup duo being joined by another Scot in Marc Warren, German Maximilian Kieffer, Dane Anders Hansen, Englishman Seve Benson and South Africa's Hennie Otto.