Beginning the final round with a three-shot lead at the K Club, McIlroy briefly gave up the lead before rallying for a three-shot victory over Russell Knox and Bradley Dredge. It marked his first victory since winning the season-ending DP World Tour Championship in November.
McIlroy had been close in recent weeks, following a T-4 finish at the Wells Fargo Championship with a T-12 finish at The Players Championship. But the Ulsterman managed to put four rounds together this week in County Kildare, a victory that is all the more meaningful considering his charitable foundation was hosting the event for the second straight year.
"I don't really get emotional when I win, but I was holding back the tears there," McIlroy said. "To play like that and finish like that, with all of my friends and family watching, was just so special."
McIlroy appeared ready to cruise to victory entering the day, but he played his first 15 holes in even par amid multiple weather delays. That allowed Knox to catch and pass him, but McIlroy took the lead again with a two-shot swing on the par-5 16th.
McIlroy's drive found the center of the fairway, allowing him to hit what proved to be the pivotal shot of the tournament - a 3-wood from 271 yards that found the green on the fly. After a two-putt birdie, McIlroy regained an advantage he would not again relinquish, closing the tournament with an eagle after another fairway wood approach from 253 yards at No. 18 rolled to within 4 feet of the hole.
It's another close call for Knox, who finished T-2 last month at the RBC Heritage and contended last week at TPC Sawgrass before putting three balls into the water on No. 17 during his third round. His lone victory remains the WGC-HSBC Champions, which he won earlier this season.
Reigning Masters champ Danny Willett led after the opening round and began the final round in second place, but he struggled to a birdie-free 77 after playing his final five holes in 5 over par. He finished T-23, 11 shots behind McIlroy.