On Sunday, four-time major winner McIlroy blitzed the elite field at Orlando's famed Bay Hill course with a final round eight-under-par 64.

The Northern Irishman's 18-under total left him three shots clear of runner up Bryson DeChambeau (68), while in-form Englishman Justin Rose (67) was third at 14 under.

McIlroy's 14th US Tour win is his first victory worldwide since claiming the Tour Championship on September 25, 2016 – the day legendary golfer Palmer died aged 87.

"I wish he would have been at the top of the hill to shake my hand when I came off the 18th green," McIlroy said of his victory on Sunday.

"The game of golf had lost an icon (that day), a legend, an inspiration to so many of us.

"It's ironic I come back 18 months on and win for the first time at Bay Hill."

McIlroy celebrates after making his birdie putt on the 18th green during the final round at the Arnold Palmer Invitational at Bay Hill. PHOTO: Mike Ehrmann/Getty Images.

The 28-year-old stormed home with four straight birdies starting at the 13th and highlighted by a chip-in from off the green at the par-4 15th.

He then drained a 24-foot birdie putt at the 18th before and emotional celebration.

"I've kept saying the last few weeks, I wasn't far away ... it's so nice to see everything come together, finally," McIlroy said.

"I've worked hard on everything, not just my putting but my ball-striking and iron play."

A host of big names threw their hat into the ring during a thrilling final day, with overnight leader Henrik Stenson carding a spirited 71 to finish fourth at 13 under.

Eight-time Bay Hill winner Tiger Woods delighted enormous crowds when he pulled within one of the lead courtesy of three back-nine birdies, but faded with two bogeys to finish at 10 under.

FINAL LEADERBOARD

The 14-time major winner iced his last tournament before the Masters with 69 to earn a second top-five finish in as many weeks.

Meanwhile, Australia's Marc Leishman signed off his Palmer title defence in style with a 67 to finish at eight under the card to sneak inside the top 10 with a share of seventh.

Jason Day, the 2016 winner at Bay Hill, was in dire straits after dropping three shots early but salvaged an even-par 72 and five under total and a top-25 result.

Fellow Australian Adam Scott was also solid on day four, posting a 71 in his last competitive round before the Masters as he earned a two under score.

Perth native Curtis Luck struggled to a 76, finishing at one over.

- Evin Priest, Australian Associated Press