The 26-year-old, now one of the NRL's best centres with Cronulla, had played just one NRL match for the Sharks before the 2022 World Cup where he shone in a win over Wales and tough loss to Papua New Guinea.
Four years later he has clocked up 61 matches for the Sharks and is at the top of his game ahead of Saturday night's showdown with Australia in Townsville.
"After the last World Cup I really kicked on after playing for the Cook Islands," he told AAP.
"I was at the Sharks at the time but I wasn't playing NRL. I was just running around in the NSW Cup for Newtown.
"Then at the World Cup I played well and it all happened for me. That is what we want for the young boys at this World Cup where we just had four debutants."
Iro has already got his wish with winger Esom Ioka, who scored three tries against New Zealand last week before tearing his calf, set to join the Brisbane Broncos on a train and trial deal next year.
"Esom is a humble person with good character and that is what people look at firstly," he said.
"On the field he is just a weapon and gets after the game as you saw with his three tries.
"He is ready for NRL and I hope he gets a crack."
Cook Islands coach Karmichael Hunt said it was "a privilege" to coach Iro who could have pledged his loyalties elsewhere.
"There was talk of KL being in the Kiwis team a couple of years ago and it was a big decision for him to pull himself out of that selection process," Hunt told AAP.
"He said that he wanted to captain our little nation instead. He is doing what the greats for Tonga have done like JT (Jason Taumalolo).
"KL is a true warrior who has put his flag in the ground and there are so many more we hope will follow in his footsteps."
Last week the Aitu were ahead of New Zealand 16-12 in Christchurch before fading to lose 82-16.
When Iro looked up at the crowd and saw the Cook Islands fans delirious at the team's heroic start to the match he had an inner glow.
"I said after the game that it was the happiest I have ever been in my life," he said.
"It was that actual moment when we went ahead of the Kiwis. I thought, 'far out, we can do this'. Imagine if we had gone on to win, it would have been crazy."
Iro is the son of Kevin Iro and the nephew of Tony Iro, both New Zealand greats. Kevin did represent Cook Islands also at Test level while Tony coached the Kukis from 2017 until 2023.
KL will make history when he leads the side against the Kangaroos.
"This is the first time we have played Australia," Iro said.
"The population of Australia is 28 million and in Cook Islands we have less than 18,000.
"For a little country like ours to be playing Australia is pretty special and I hold that high in my heart. It makes me really proud."