The Queenslander, who now lives 10 minutes away from TPC Sawgrass in Florida and plays it regularly, outlasted Anirban Lahiri by a single shot across a marathon five days as rain caused constant interruptions for the elite field to claim the biggest purse in US PGA Tour history on the back of a putting masterclass.
"It's huge. It's gonna take a while to sink in," Smith said.
"I live here now, I call this place home and had a lot of fans out there rooting for me.
"(Putting) was the big key today, it kept me in it. I made plenty of birdies and had to make a lot of good par putts at the end there. It's definitely the strength of my game and sometimes I maybe lean on it too much, but it's nice to see them go in."
With family, including his mother and sister who Smith hadn't seen in more than two years, and his best mate following every shot from behind the ropes, he needed nerves of steel after making a last-hole error having almost iced the tournament after a stunning wedge to the famous island green on the 17th hole.
Smith, who had to play 26 holes on the final day, rolled in the birdie putt, his 10th for the round, which matched the record for TPC Sawgrass, to give him a three-shot buffer as he headed to the 18th hole.
But having twice put his tee shot in the water on the closing hole in earlier rounds, Smith again missed the fairway, but this time well right, a long way from the wet stuff.
His punch out from the trees rolled all the way across the fairway and found the water where two of his balls already lived.
As Smith found water on 18, Lahiri made a crunch birdie on 17 playing behind him to narrow the gap to two shots.
But Smith met the challenge, with a wedge to 1m and a tap-in bogey that demanded Lahiri made a birdie to force a playoff.
Lahiri missed the green with his approach, couldn't chip in for birdie, and the $4.9m winner's cheque belonged to Smith, who finished at 13-under after a closing round of 66, with his 101 putts for the tournament the fewest ever for a champion.
Smith was emotional about the presence of his family who saw him plant a flag ahead of another tilt at the Masters next month.
"I haven't seen them in two years. It's really cool to have them here," he said, choked up.
"My main priority was to hang out with them and golf was second for the last few weeks. It was good to see them and nice to get a win for them."
