McIlroy expressed delight at the success of this week's Ballyliffin event after the European Tour's decision to bring the tournament to the Donegal venue for the first time.
It was then left to Knox and he delivered in the final holes to set the mark at -14, which was equalled by Ryan Fox, but in the play-off the Scot proved himself with that repeat 40 foot putt.
Knox put his second shot in a position nearly identical to the one he found on the 72nd hole and rolled it home again, with Fox missing his own birdie attempt from 12 feet.
Knox now has a Rolex Series win to add to his WGC-HSBC Champions crown from 2015 and continues his fine form after finishing in a tie for second at last week's HNA Open de France.
'I've already holed this one, so how hard can it be?' said Knox, jokingly, to his caddy James Williams.
"I'm excited and slightly nervous because Carnoustie is a bit of a beast".
Kim shoots 31-under 257, shatters LPGA scoring records
During the final round, Kim showed outstanding accuracy with her iron shots, with a Greens in Regulation percentage of 94.4. Kirk had led by one after a first-round 62, but she couldn't get it going on the greens Friday and settled for a 71.
"I was able to hit a good shot and get on the green, which I was thrilled with", Knox said of the putt.
"For me to have made it twice in a row.I'm very lucky".
Russell Knox's hopes of making this year's European Ryder Cup have received a significant boost with victory in the Irish Open. "I hit two great putts on 18 and one grazed the edge and one came back at me".
South African Van Rooyen entered the day with a four-shot lead and while he birdied the fourth, bogeys at sixth, seventh and ninth meant he had been caught by Campillo at the turn.
Speaking about the two putts on the 18th, Knox added: "It's why I play golf, all the practice, all the misses, all the bad moments are taken care of with putts like that". Each time Knox responded, with the pair the last ones standing in a round where several players launched bids at the title.
With overnight leader Erik Van Rooyen feeling the pressure, Knox moved into a three way tie for the lead with Fox and Spaniard Jorge Campillo - who set the clubhouse target with a brilliant 65 - following birdies at the 12th and 15th.
Knox had finished second to McIlroy in the 2016 Irish Open at The K Club after the host produced two magnificent blows over the closing holes.