The outcome was never seriously in doubt at Marco Simone on Sunday (Monday AEDT) as Europe started the final day with a five-point lead with McIlroy, Jon Rahm, Viktor Hovland and Tyrrell Hatton then putting them on the verge of regaining the cup and forcing the US to win the remaining five matches on the course.
Just like everything else this week, there was little chance of that.
McIlroy was still fired up over what he perceived to be bad behaviour by Patrick Cantlay's caddie Joe LaCava on the 18th green the previous evening. Europe's champion won his match to cap a 4-1 week and was the team's top scorer for the first time in a Ryder Cup.
Then Fleetwood, whose brilliant partnership with McIlroy over the week was inevitably christened 'Fleetwood Mac', hit a superb signature shot on the signature hole, a drive to 25 feet on the reachable 16th.
Rickie Fowler hit into the water and eventually conceded a short birdie to the popular Englishman that assured Europe the 14 1/2 points they needed to claim the 17-inch gold trophy.
The celebration was on, just like it always is on European soil, with one exception. The first Ryder Cup in Italy brought its share of chaos as fans raced toward the edge of the 18th green to watch the final match that only decided a result for the record book - Europe 16 1/2 United States 11 1/2.
The Americans were coming off a record 19-9 win over Europe two years ago at Whistling Straits, confident this would be time they ended 30 years of losing away from home.
Make it 34. They won't get another chance until Adare Manor in Ireland in 2027.
"We were so disappointed after Whistling Straits. We all were," said McIlroy, who was in tears at the last Ryder Cup.
 "We wanted to come to Rome and redeem ourselves. I just knew I needed to put in a better performance for my team this week."
"I think the European team played some phenomenal golf. I think it really is quite that simple," US captain Zach Johnson said, his voice choking to the point it was hard for him to complete a sentence. "Team USA will be better for it. We'll figure it out."
Scrutiny is sure to follow. His six captain's picks combined to win four matches all week. Only three Americans played a tournament in the five weeks since the PGA Tour season ended.
The Americans made Europe sweat, but only briefly.
Rahm won the 18th hole to earn a half-point against Scottie Scheffler. Hatton completed an unbeaten week by beating British Open champion Brian Harman. Hovland put the first blue point on the board in a win over Collin Morikawa.
All Europe needed was one more half, and Fleetwood assured that with a 2-up lead with two holes to play against Fowler.
Patrick Cantlay gave his team momentum even in the face of fierce heckling for not wearing a hat and a Sky Sports report he called "outright lies" that he was not wearing a hat to protest not being paid to play. For two days, thousands of fans waved their caps at Cantlay, who never flinched.
He birdied his last three holes Saturday evening in fourballs, and then McIlroy was furious with LaCava for continuing to celebrate as McIlroy still had a putt.
McIlroy said he used it as fuel.
"I didn't let it take away from what's been a fantastic week," he said. "I think what transpired on that last green gave us a fire in the belly to get the job done."
