The four-time major winner signed off his sixth appearance in the biennial event with a 3&2 win over Olympic champion Xander Schauffele in the closing singles session at the Wisconsin venue.
However, that was McIlroy’s sole success in four matches over the three days, having been left out of a session for the first time in his career on Saturday morning despite Europe trailing 6-2 after the opening day.
And, though he enjoyed silencing some critics in leading by example for Padraig Harrington’s team on the last day, McIlroy was quick to hold up his hand as the Americans coasted to a resounding victory.
“I love being a part of this team, I love my team-mates so much and I should have done more for them this week,” said the Northern Irishman, who had to stop a couple of times as he was being interviewed to try and compose himself.
“I’m incredibly proud to be a part of this team, to be a team-mate of all these guys, the captain, the vice-captains. We've had a great time.”
McIlroy had been one of the nine automatic qualifiers for Europe’s trophy defence, but, alongside Ian Poulter, he lost the first five holes in Friday’s opening session in going down 5&3 to Schauffele and Patrick Cantlay.
He was then sent out with Shane Lowry in the fourballs only to lose that one 4&3 to Tony Finau and Harris English before suffering another outing with Poulter in the Saturday fourballs which resulted in a 4&3 loss to Dustin Johnson and Collin Morikawa.
It was more like it as McIlroy found his game to sign off on a high, but, though pleased about that, he added: “I've been extremely disappointed that I haven't contributed more for the team.
“It's been a tough week. And the more and more I play in this event, I realise that it's the best event in golf, bar none. I love being a part of it. I can't wait to be a part of many more. Yeah, it's the best.”
McIlroy, who will get his chance to make amends in the 2023 contest in Rome, is hoping this Ryder Cup and the recent Solheim Cup, won by Catriona Matthew’s European team, will have inspired youngsters.
“I don't think there's any greater privilege to be a part of one of these teams, European or American,” he said. “It's an absolute privilege. I've gotten to do this six times. They have always been my greatest experiences of my career.
“I have never really cried or got emotional over what I've done as an individual. I couldn't give a s***. But this team, and what it feels like to be a part of, to see Sergio [Garcia] break records, to see Jon Rahm come into his own this week, to see one of my best friends, Shane Lowry, make his Ryder Cup debut.
“All that, it's phenomenal and I'm so happy to be a part of it. As I said I'm disappointed that I didn't contribute more this week, but, in two years' time, we'll go again and go again.”