Henley's birdie at the first playoff hole allowed him to recover from a shaky back nine where blunders at the 10th, 12th and 15th threatened to blow his chances of victory but the man who led into the final day, McIlroy, was also having his troubles.
McIlroy bogeyed the 12th, doubled the 16th and then bogeyed the 17th after his outward nine had also contained errors. The Northern Irishman had led form his brilliant opening round of 63 but faltered over the closing holes to allow Henley the opportunity which he accepted willingly.
Stuart Appleby finished as the leading Australian in a share of 8th position while Adam Scott returned from a six week break to finish tied for 12th ahead of his first WGC Championship next week at Doral.
For Appleby it was his best finish anywhere since his 7th place finish at the 2012 Australian Open.