The 25-year-old AG2R Citroen rider stunned the peloton with a sensational ride to the top of the French alps, finishing first in the ski-resort village of Tignes by more the five minutes ahead of Italian Mattia Cattaneo.
The West Australian now sits second in the general classification, two minutes behind reigning champion Tadej Pogačar of Slovenia.
In a column for , O’Connor revealed his emotions after reliving the greatest victory of his burgeoning career so far.
“Today has been pretty calm – coffee, calls, a ride, physio stuff – but last night was special. A lot of tears were shed,” O'Connor said.
“The process of trying to comprehend what you’ve done begins when you cross the line, and it starts with shock.
"I knew I was going to win the stage for a while, but there’s still that moment of awe, especially when you stop having to climb up this massive mountain.
"I was just gasping. It was madness. It took a while to regain my composure.
“One of the first people I saw was our team manager, Vincent Lavenu, and it was cool how emotional he was. This means so much for a French team.
"He said ‘you're a champion today, you're THE champion today, you're our champion'.”
With still 12 more stages to ride, O’Connor had to hold off truly letting loose in his celebrations later that night.
The Fremantle product said he did enjoy a beer and a champagne or two, while thanking his team for their efforts in helping him achieve his incredible triumph.
Suffering a fall on stage one, O’Connor admitted he thought his Tour de France was done and dusted.
“I could never have imagined this a week ago. I thought my Tour de France was done on day one," he said.
“The thing is, I already have this stage win, so I don’t think I have to worry. I’m not thinking ‘ah I have to make the podium now’. No. I’m going to ride as fast as I can and if it’s not fast enough, voila.”