Having his ninth ride in the Melbourne Cup, James McDonald positioned Verry Elleegant midfield and one off the rail.
The daughter of Zed crept closer from the 800m and was poised on straightening, hitting the front with 300m remaining and drawing clear to register a four-length victory.
"I just didn't think this day would ever happen," McDonald said.
"I ride in these races, I really want to win but sometimes you can overthink it and try too hard.
"I was very confident in the mare today. Thoughts (of winning) went through my mind at the 500m when I saw Incentivise getting shoved along but I knew he would fight. There wasn't a horse that was going to come from behind me, it was just a matter of catching him.
"Like I've said since Saturday, there wasn't another nine-time Group 1 winner in that race - she was it. I wouldn't have thought there was one other horse in that field I thought could run third in a Cox Plate. She was ready for it."
The leading Sydney-based jockey has come close to claiming the Melbourne Cup in the past, namely when finishing a narrow second on Fiorente in the 2012 Melbourne Cup and also running third aboard Hartnell in the 2016 renewal.
"To pilot horses like Verry Elleegant each and every carnival is just a huge privilege and it worked out really well for us today," McDonald said.
"It doesn't always happen like that and you take the good with the bad but today we were lucky enough to win a Melbourne Cup."
McDonald and Verry Elleegant in winning the 2021 Melbourne Cup also provided trainer Chris Waller with his first victory in Australia's feature staying event.
Waller's best result in the Melbourne Cup from 22 prior runners was a third in 2014 courtesy of Who Shot Thebarman.
"He just goes through his processes and makes sure every box is ticked," McDonald said.
"It is why he is as good as he is.
"I am so lucky to be in his team. We have a lot of luck together and we know each other so well."