The three-time major winner, who revealed he’d been offered the chance of eight wildcards at one point due to the Covid-19 pandemic, eventually settled for just three.
They went to Lowry, Sergio Garcia and Ian Poulter after a two-year qualifying race ended following the BMW PGA Championship at Wentworth on Sunday.
Lowry had been in one of the nine automatic spots heading into the Rolex Series event only to be knocked out by Bernd Wiesberger, but his disappointment was short-lived after receiving the good news from the European captain.
“It really is one of the better parts of the job,” said Harrington of making that particular call. ”I've been around Shane the last two-and-a-half years and it's the elephant in the world, no doubt about it.
“Everybody says, you're going to pick Shane, you're going to pick Shane, and if anything that pushed it away from me. It actually made it harder for Shane to get in the team.
“Thrilled with the way he handled the pressure throughout this year. His consistency, his form has been tremendous. He really pushed on during the latter half of the season.
“I had to keep checking with the vice captains and say, ‘you know, I'm not biased here. Don't let me be distracted here because Shane is my friend’. It was with the support of the vice captains, I was able to give him the nod.”
Lowry, Garcia and Poulter all got the nod ahead of Justin Rose, who was Europe’s star player in the 2014 win at Gleneagles, while Alex Noren had also been in the frame for a pick.
“At one stage during Covid, I was offered eight picks,” revealed Harrington. “Because it was very broad in Covid, we were thinking no golf for six months into the Ryder Cup.
“You might have had 20-plus people who might have a thought of making the team. That's 730,000 combinations of teams you can make up out of that.
“I chose to have three picks and I'm very comfortable that that was the right decision. It was tough leaving Justin Rose out. There's always going to be somebody on the bubble.”