A one-under round of 70 on Friday left the world number three well positioned to challenge over the weekend, just two shots behind Matteo Manassero's leading mark of six under par.
The highlight of McIlroy's round was an eagle on the par-five first, his 10th hole of the day, but the home favourite covered his other 17 holes in one over.
"It was just a matter of making sure I was here for the weekend and give myself a chance. Sort of job done for the first two days and turn my attention to the weekend," said McIlroy.
"It's much better than nine years ago here when I was watching the third round on TV. Happy to be here for the weekend and happy to give myself a chance."
Italy's Manassero made a flying start to his second round with an eagle on the first followed by birdies on the second and third, with another eagle coming from tap-in range on the par-five 12th following a stunning approach.
"Links golf makes you hit really difficult shots, everything has to be right. It takes a lot of energy out of you, but when you're playing well the adrenaline kicks in and I'm looking forward to tomorrow," said Manassero, the world number 127.
England's Todd Clements and Laurie Canter are Manassero's closest pursuers on five under
Spain's Alejandro del Rey had also eagled the first and looked set to post a testing target when he reached eight under par, but ran up a quadruple-bogey eight on the 15th to finish alongside McIlroy and Scotland's Ewen Ferguson on four under.
