The Northern Irishman returned to the winner's circle courtesy of a scintillating eight-under-par 64 that included five birdies in the final six holes.
"It's just so nice to see everything come together finally". "I wasn't that far away". "It would just take something to click into place and something clicked into place with my long game". "Something clicked into place with my putting obviously".
DeChambeau eagled the 16th but missed from five feet to save par at the last to finish three strokes back, with Rose in third after three birdies in a five-hole stretch on his way to a five-under 67.
"Just to be able to create my own little bit of history at the 18th green here is pretty special and I'm just really proud of myself to have hung in there over the last few months". "I've had a lot of success there, too, so really looking forward to getting up there and doing a bit of work and getting a feel for the golf course and basically feel for playing that style of golf again".
The 28-year-old from Northern Ireland took his 14th US PGA Tour triumph, his first since the 2016 Tour Championship, and served notice he is a solid threat to complete a career major Grand Slam by winning the Masters in three weeks.
The victory - McIlroy's first since the day Palmer died, September 25, 2016, and his 14th PGA Tour W - was bittersweet.
"It's a little bit ironic that I come here and win", McIlroy said. If I hit driver I got to fit it, I've got to cut it in there.
McIlroy stormed home with four consecutive birdies starting at the 13th, before draining a 24-foot birdie putt on 18 - prompting an emotional fist pump.
"I miss playing there", Woods said.
McIlroy made the turn in 3-under 33 after running off three birdies in his last four holes on the front.
But before McIlroy could get to his second shot, DeChambeau turned up the pressure with an eagle at 16 to trim the advantage to one.
McIlroy charged into a share of the lead early, opening with five pars before making back-to-back clutch birdie putts, a 10-footer at the sixth and 12-footer at the par-3 seventh.
The former world No 1, making his fifth start since spinal fusion surgery, continued his impressive return from injury to briefly threaten the top of the leaderboard on his way to a final-round 69 at Bay Hill.
While it was disappointing end to promising week, the 14-times major victor will take away plenty of positives as he looks ahead to next month's U.S. Masters.
"I felt pretty good out there". "I didn't decide what I was going to do". "I had three different shots. I bailed out and hit a bad shot and that's on me for not committing".
Woods made a bogey at 17 and closed with a 12-foot par putt.