The 32-year-old had built enough of a lead that he could enjoy the greatest walk in golf up the 18th fairway knowing the Claret Jug was waiting for him, and has become just the second Irishman to lift it, after Padraig Harrington.
He eventually signed for a score of 72 which saw him end the Championship at -15 and Fleetwood could only shake the new Champion Golfer's hand as he finished six strokes back.
American Tony Finau produced a superb level-par 71 to finish third at -7.
Last year's Champion Golfer Francesco Molinari also finished strongly with a Sunday-best round of 66 that saw him leap up to -3 for the Championship and a tie for 11th.
Lowry was greeted by boisterous fans who belted out football chants and pop songs lauding their hero long into the night.
"Honestly, that's the most incredible day I've ever had on the golf course. I honestly can't explain what it was like," said Lowry afterwards. "The crowd was incredible," he said.
"I let myself enjoy it and it was incredible walking down 18, they were singing and going mad. I could not believe it was happening to me.
"It is huge for Irish golf and big for Irish sport. I am a huge sports fan and I think there are people back home who watched golf that have never watched it before," he added.