World No. 2 Vijay Singh is the top player in the field and he posted a 4-under-par 68. The Fijian shares second place with Ricardo Gonzalez, who is a three-time winner on the European Tour, and Thongchai Jaidee, the two-time defending champion at the Malaysian Open.
Charl Schwartzel was joined in fifth place at 3-under-par 69 by Ross Bain, Peter Gustafsson, David Lynn and Henrik Stenson.
Horne opened with four straight pars at Abu Dhabi Golf Club. He then dropped in a birdie putt on the par-4 fifth to get into red figures. After parring the sixth, the 34-year-old converted a birdie on the seventh.
The South African made it two straight as he birdied the par-5 eighth. Horne birdied the next par-5, the 10th, to move to 4-under.
Horne continued his climb up the leaderboard with a birdie on the par-3 12th. Horne carded his final birdie at No. 14 before he parred his final four holes.
'It was very good out there today,' said Horne. 'I hit the ball nicely and I just tried to concentrate on hitting the ball well today and not getting ahead of myself, which I tend to do, so I was very happy with my round. It is the first time I have played a European Tour event which is not co-sanctioned with another tour so I am enjoying it very much. It is a big event with a lot of good players so I am just trying to absorb it all.'
Singh played the back nine first on Thursday and began his round with a birdie on No. 10. He parred his next seven holes before dropping in a birdie on the 18th.
Around the turn, Singh moved to 3-under with a birdie at the par-3 fourth. He then birdied the next par-three, No. 7, to close out his round.
'It was pretty tough out there with the windy conditions,' Singh said. 'When we started off it wasn't as windy, but as we got along, it got really windy and dry. It was tough. I was really pleased with the score I had, and I had a lot of opportunities out there to even better it, but I'll take a 68 today.'
Gonzalez also began on the back nine. He converted consecutive birdies from the 12th. The Argentine bogeyed 15, but got that stroke back with a birdie on the 18th to make the turn at minus-two.
He poured in back-to-back birdies from the first to get to 4-under. Gonzalez got within one of the lead with a birdie at six, but he tripped to a bogey at the next to end two back.
Jaidee got his round going with a birdie on No. 10, his first. He moved to minus-two with a birdie at the 14th. The 36-year-old made it two straight as he birdied the 15th as well.
The Thailand native sank a birdie try on the first to move to minus-4. Jaidee made it two straight as he then birdied the second. After running off six straight pars, Jaidee bogeyed the ninth, his last to finish at minus-4.
Sergio Garcia, the sixth-ranked player in the world, posted a 2-under-par 70. He shares sixth place with 11 other players including Richard Green, Miguel Angel Jimenez, Jose-Filipe Lima, Gonzalo Fernandez-Castano and Alastair Forsyth.
U.S. Ryder Cupper and world No. 11 Chris DiMarco is one stroke further back at minus-one. He is joined there by 11 other golfers.
John Daly and Colin Montgomerie are in a group of 14 players sitting at even-par after the opening round. Daly recorded four bogies and four birdies, including only one birdie on the courses four par-5s, to card his 72.