Northern Ireland's US Open champion, who shocked the golf world by changing management stables just over a week ago, stands 18 under par and bang on course for the record £1.25million winner's cheque.
McIlroy, trying to complete a wire-to-wire victory just as he did for his first major title in June, did not drop a stroke all day and turned in 32 with birdies at the first, third, seventh and ninth - the hole he double-bogeyed in his second round 69.
The 22-year-old world number three then picked up more shots at the 13th, 15th and 16th.
Kim, who failed to retain his Ryder Cup place last year after undergoing thumb surgery, matched McIlroy's round, but made his final day task all the tougher by finishing with a bogey.
Twenty-year-old Korean Noh Seung-yul is in third place, but a 67 left him four back and there is then a further three-stroke gap to England's Ian Poulter, also round in 67.
World number two Lee Westwood produced only a 70 and alongside Australian Geoff Ogilvy in sixth place is now 11 adrift.
Padraig Harrington, Colin Montgomerie and Paul Casey all disappointed with 73s. Harrington dropped to eighth, Montgomerie to 12th and Casey to 17th in the 30-strong line-up.