The bang in-form target man has already bagged himself 16 Premier League goals so far, and a further 9 in other competitions. He's now on the brink of a call-up to the England squad after a much-publicised meteoric rise.
Last year, however, O'Neill revealed in an interview that he was eyeing a specific player at the London side.
Speaking ahead of the upcoming game against Poland, he said he was given reason to believe that Kane was ready to switch allegiance and pledge for Ireland.
"The order of events is that initially the agent got in touch and said that he would have a keen interest and we wanted to go and chase it up," said O'Neill. "But then I noticed in the newspaper where he said he wanted to play for England.
"That has remained the same. Someone was speaking to him recently and that was exactly the same conversation. Fine, if that's the case. Harry himself always wanted to play for England. It's just as simple as that.
"It would have been really nice. There's a fairly decent chance he might have had a few caps for us before he actually plays for England considering the way he's playing.
"Sometimes what agents do is they have someone who looks after the player who is not actually licensed to buy or sell or be involved as an agent but he was the one who called. He happened to call me on a day when Harry Kane said he wanted to play for England."
Bournemouth starlet Harry Arter, capped by Ireland at U-19 level, is the newest face O'Neill has drafted following his form at the Championship side.
"Harry is having a very good season at Bournemouth and Bournemouth are having a brilliant season. I've seen him a bit and thought, 'Yeah, why not?'
"It's a chance to add another fresh face," said O'Neill.